I have an occasional tendency to make icons from the pretty art, although I am trying to cut down on this. If I knew Japanese, I would email the artists to ask permission. As I do not, I can at least give credit in the form of links. This post will do that, and it will also provide links to some of my favorites fanart sites.
This comes from the "Fullmetal Bean" doujinshi by Wolfgung. It is the cutest and most hilarious FMA doujinshi ever, and it can be found here.
This is one of my favorite icons. It comes from this page, which has some really lovely art, primarily (but not entirely) Hughes, Mustang, and Hughes/Mustang.
Another of my favorite icons. This one is from here, which has some very nice Kakashi fanart, although unfortunately most of it is KakaIru. (No, I do not like that pairing. It's not really that I have anything against it; it's just that it has no reason to be probably the second-most popular pairing in a fandom with so many better pairings.) My permission to use this icon can be found here. I'm working on getting permission for the other ones, really.
This one comes from here, which has a distressing amount of Seifer/Squall, but also a lot of adorable chibis.
This one's from candy*store, my favorite Naruto fansite evar. It has THE BEST TemaShika arts out there, as well as some just plain awesome Shikamaru arts. Lots of adorable crack-chibis.
This is from the "Sunny Side River" doujinshi by the circle Konjou Komiai (artist Fujitani Yoko).
From Mr. Randomness. Smallish gallery of beautifully drawn images, mostly Bleach and some stuff I've never heard of.
From Nephrite, a smallish but expanding gallery of lovely Bleach fanart, including some very nice Rukia art.
From fanart by Pika, who has given her permission for me to use this icon.
These are from the "Chadokoro" doujinshi by the circle Rensougyo (artist unknown).
This is from the hentai doujinshi "Yami En Bu" by the circle Strawberry Nipple.
This comes from the yuri/futanari doujinshi "Orihime-chan De Go," by the circle U.R.C.
I don't know the name of the doujinshi this Terra icon comes from (it's only in Japanese), but the artist is listed as Karko Watanabe.
This Kanda icon is from art by wreeth.
This Kimimaro icon is from Retonomiyako, which is full of adorable Naruto and D.Gray-man fanarts.
From gift art by chozo. Don't ask.
I've lost the source for the following icons. If you find the sources to any of them, please comment and let me know.
Fandoms: FMA (Fullmetal Alchemist), FF[#] (Final Fantasy; sometimes more specific), SO3 (Star Ocean: Till the End of Time), Naruto, Bleach, DGM (D.Gray-man)
Warnings: C (toxic levels of cuteness), WTF (lots of bizarre crack), Y (includes yaoi), H (it gets explicit).
Comment and let me know if I've gotten anything wrong or forgotten a warning.
Miya Nenone -- FMA etc. Mostly art of Ed and Al, with some Winry; occasionally other characters. C
Akira -- FMA. Probably my favorite Hughes fanart on the whole wide intarweb. She does pretty Havoc, Roy, and Ed arts as well; the only character I don't like her depiction of is Hawkeye, and she even occasionally manages a good one of her. Y, a little H
Two in All -- FMA. Just very nice FMA fanarts in general.
Katsushika Dress -- FMA. Really, really nice fanart, very official-looking in style, with a focus on Ed.
Reiko -- FMA. Good Ed-focused arts, although a few too many pinup-ish ones for my preference, but sometimes I think I'm the only person in the fandom who doesn't see Ed as some kind of delicious teenage sex object.
Rhythm to Heart -- FMA etc. Your one-stop source for cutesy explicit FMA yuri! H, WTF
Kameyashiki -- FMA. Some very nice Mustang and Havoc art; some Hughes art as well which I don't care for quite as much. They also have a Naruto-centric site, Sannasubi, but that's mostly so-so KakaIru. Y
Meteolight -- FMA, Naruto, etc. Aggravatingly hard to navigate, but has some good comics. Beware the Jiraiya/Yondaime linked to at one part of the site. Y
Shichiyoh -- FMA, Naruto, etc. Some very pretty Uchiha arts, mostly in comic format, although unfortunately some of it is Uchihacest. Y
Ronronshuka -- Naruto, SO3, etc. Awesome sannin cuteness. And Tsuboobies. H
Deep Forest -- FFVIII, some other FF. The best Squall fanarts I've seen, although I am vaguely bothered by the fact that last time I checked, there was more Seifer fanart. Oh well. There is a lot of Seifer/Squall, but it's clearly labeled, and even most of that is gorgeous. Y
Honeybee Manor -- FFVII, some other FF. Tons of Cloud, Sephiroth, and Vincent art (not to mention a goodly number of arts of the girls), done in a style amazingly like the better official art. The only website I've seen with any quantity of Vincent/Lucrecia arts.
Love Drop:B -- Bleach. Lovely, lovely IchiRuki, as well as some RukiRen and some of Ichigo, Rukia, and Renji alone.
Cross and Skull -- Bleach, Naruto. Some very pretty Bleach and FMA fanart.
Yuccoshi -- FFVI, some other FF. Absolutely lovely FFVI fanarts.
Magnolia -- FMA etc. Beautiful Hawkeye and Hawkeye/Mustang arts.
Lanlingjiujia -- FMA. Exceedingly pretty art, mostly of Roy/Riza, but also some other stuff.
Neko Moyou -- FMA. Most adorable Roy/Riza in existence. Also has some great stuff of other characters.
crazy9 -- FMA etc. One of the few fanart interpretations of Hughes that I really like. Y
Ougizakura -- Naruto. Lovely, lovely SasuSaku arts (as well as some others).
StrayCatFever -- Naruto. Painfully cute Sasuke art, as well as some nice Itachi stuff. Unfortunately also includes a bit too much Kakashi/excessively-young-looking-Sasuke,
Silent Sea -- FMA, Naruto, etc. Adorableness. Lots of Naruto stuff, some FMA as well. C, Y
Israk -- Naruto, FF, etc. Gorgeous art of Hinata in particular, but also of other characters. Mostly NejiHina.
Hanamaru -- Bleach. Lovely RenjiRuki and HitsuHina, as well as great art of other characters as well. H
Revia -- Bleach, Naruto, etc. Very nice Rukia art, as well as HitsuHina and other stuff.
[KETO] -- Bleach. Really lovely Rukia art. Unfortunately not much of it yet, but hopefully there'll be more in the future. H
nekos -- Bleach. A bunch of good art, primarily of Hanatarou, despite all the crackpairings centered on him. Y
Child Cat -- Bleach, Naruto, DGM, etc. Aside from...remarkably good tentacle porn, this site also has some regular porn which is actually decent. But it's almost all porn in any case, so tread carefully. H
Aidma -- Naruto. There are no words for the sheer cuteness. None. C Direct link not working. However, copy and paste it into your address bar. The cuteness is worth the trouble.
Uzu-ringo -- Bleach, Naruto, etc. This, too, has much cuteness, as well as some very nice art. C
Kichijitsu -- Naruto etc. Gorgeous art, primarily Uchiha-focused.
grappe -- Naruto. Similarly lovely art, with a focus on Itachi, but other stuff as well.
PochinokoPro -- Naruto etc. Very nice SasuSaku fanart.
en-ju -- Naruto, FMA, etc. Very pretty art, if somewhat oddly stylized. Primarily Hinata, Neji, and Kiba.
pororin -- Naruto etc. Very clean, official-looking art, and a lot of it.
Haliack -- Naruto, DGM, etc. Pretty, interesting fanart, although somewhat oddly stylized. Y
10-rankai -- Naruto etc. A lot of wonderful Naruto fanart, with some especially good pieces of Sasuke.
KururuDENPA II -- Bleach, Naruto, DGM, etc. Some whacked-out pairings, but a lot of cute stuff, all the same. Lots of Orihime art. Y
Love Reach -- Bleach etc. A lot of Ichigo, a lot of Ishida, some of them together, and a few other things, all of it well-drawn. Y
baby* -- Bleach etc. Some very nice pictures of Urahara and Ichigo in particular. Unfortunately, they are together entirely too often... Y
invivi -- Bleach. Has a very nice collection of fanarts, with a lean towards IchiHime and Ukitake.
Nowhere -- Bleach etc. A lot of adorable art focused particularly on the 11th Division, especially Yachiru. Also a fair amount of Rangiku. C
Celluloid Acme -- Naruto etc. Stuff from here tends to show up on 4chan a lot. Some of it's very weird, but there's a lot of well-drawn and extremely sexy art as well. H, WTF
Echigoya -- Naruto. Some very good art, especially of Itachi. There seem to be some slashy bits, but nothing major.
Miduki Akira -- Naruto etc. Nice art, with an unusual number of Shikamaru and Kiba pictures.
keroyon jima -- Naruto etc. A lot of adorable NaruHina as well as some nice art of others. Besides being cute, the art is excellent. C
Fem -- Naruto etc. Despite the occasional OroJira and other such disturbingness, some very nice art. Y, C
Negiko -- Naruto etc. A wellspring of Team 10 cuteness, particularly as regards Shikamaru. Also includes some ShikaTayu crack. C
White Knight's Pearl -- Naruto, FMA, etc. A lot of art, particularly of Shikamaru. Some cute ShikaIno.
Rouge Attic -- Naruto etc. Very pretty art, including some quite nice watercolors. Some KakaSasu, but also a few very nice SasuSaku pieces. Y, C
Supermanic Soul -- Naruto. Despite an exasperating overabundance of KakaIru, this site has some very nice art, especially of Kakashi. Y
Area 325 -- Naruto etc. A wide variety of very clean, attractive art.
Netkaryu -- Naruto, FMA, etc. Lots of silly cuteness. Y, C, WTF
Happy Collection -- Naruto, FMA, etc. An assortment of Team 10 cuteness on the Naruto side as well as some nice FMA art. C
Switch -- Bleach etc. The quality here is hit or miss, but when it hits, it's great. Some very nice art of Renji and Shuuhei in particular. Y
Mad Mush -- Bleach etc. A collection of fairly nice, clean art. Big on the male fan favorites--Renji, Shuuhei, Izuru, and Hitsugaya. There are others as well, though.
Crystal Little Clover -- Bleach etc. Has a fairly wide range of nice art, with a bit of a lean towards HitsuHina.
Hariya -- Bleach etc. Has a lot of very cute art, particularly of the Karakura Town characters. C, WTF
97 -- Bleach, FMA. A lot of very cute art as well as some prettiness. Lots of HitsuHina. C
Kuzuya -- Bleach etc. Some pretty art, with a preponderance of Soi Fong.
AZupper -- Bleach etc. Has some of the most well-characterized Rukia art I've seen--her expressions are perfect.
Concrete Girl -- Naruto. Very clean, pretty art with a distinct lean towards Team 10. Lots of ShikaIno, some NejiTen and a bit of NaruHina as well.
Fade to Black -- Naruto. Some nice art with a particular focus on the Sand brothers (not so much Temari, sadly).
Big Tree -- Naruto, FF, etc. Strangely adorable art. The general site actually has some very cute Harry Potter art; the Naruto-specific site (Sweetness) has a lot of lovely SasuSaku. C
route 066 -- Naruto, DGM, etc. A bunch of well-drawn and often adorably amusing pictures. C, WTF
Honey Hive -- Naruto etc. A bunch of hot Kakashi pictures and a few images of other characters as well.
Cahoot -- FMA. A smallish selection of very nice art. Has some of the few Hughes fanarts on the web that I actually like.
Tomahawk Baiser -- Naruto. Some very cute art, with an emphasis on NaruSasu. C, Y
Shiro-Usagi -- Naruto. Elegantly drawn art with a focus on Yondaime.
Fakefur -- Naruto, Bleach. Some gorgeous Yondaime art as well as a lot of Izuru images (including both Gin/Izuru and Renji/Izuru). Y
Magnet000 -- Naruto, Bleach, etc. Rather hard to navigate, but worthwhile for the quality. Much of it is lineart, but even that's pretty. Very nice Sakura art.
Deeva -- FMA, Naruto, etc. Sakura is a little too young-looking in a lot of this art, sometimes badly so, but a lot of it is actually cute. The FMA section also has terrific Roy/Riza art. C
Slowcat -- Naruto etc. Some clean, well-drawn art. Definitely on the cutesy side. C
Hanainu -- Naruto. Pretty art with a focus on Team Gai.
Tierra -- Naruto, FF, etc. A little hard to navigate, since the art isn't divided by fandom, but worth it for the pretty Naruto arts. Some very nice Sasuke art.
torori -- Naruto etc. The art here is rather too cutesy at times, but some of it's nice. C
Sunny Funny -- Bleach, FMA, FF etc. Some pretty fanart, particularly of Gin and Renji on the Bleach side. The FF section has some good Turk pictures.
plastic trance -- FF7 etc. Some unusually good FFVII fanart. WTF
sugar-less -- FF7, FMA, Bleach etc. Mostly FFVII art, most of it oekaki-ish, but all of it interesting. Notable for a lot of Turk fanart and a focus on Reno.
Kurumi-Show -- Bleach, FMA etc. Some very attractive art, focusing mainly on Gin/Izuru and Hitsugaya/Hinamori. Beware the Shunsui/Aizen crack, though. Y, WTF
Hiro -- Naruto. Exceptionally beautiful art with a focus on Itachi, although several other characters are represented as well.
Plum tea Maniac -- DGM. Slightly untidy but attractive art with a tendency towards Rabi/Kanda. Y
Ebony Birds -- DGM. A small but growing collection of arts. Lots of sketchy Cross. Y
Alpha -- DGM. Has a wide selection of arts, including most characters. Notable for some pretty Cross. Y
Mangifera indica's Storage -- FF7, Bleach, etc. A small but very striking collection of arts.
Sometime -- FMA, Naruto, etc. An excess of Roy/Ed, but some very good art, especially of Team 7 in the Naruto section. Y
Zeolite -- DGM. The quality varies a bit (some images are sketchier than others), but a good DGM fansite in general. Y
Silent Robin -- Naruto etc. Gorgeous art with a particular focus on Naruto and Kakashi.
H+E+Y -- Naruto. Some of the art is sketchy, but it's all fairly good and there's a lot of it.
Testament -- Naruto etc. Some extremely pretty, well-done art. There really should be more.
22 -- Naruto, FF, etc. Gorgeous arts, mainly of Yondaime, with some FFVII thrown in on the side.
re:LT -- Naruto. Adorable, pixel-ish art with a lot of Kakashi. C, WTF
D.co -- Naruto etc. Not fanart, exactly, but adorable little pixelated icons. It's worth a look. C
Seventh Heaven -- Naruto etc. Several very artistic-looking pieces; a number of Kakashi fanarts in particular.
Piero -- Naruto etc. Some very pretty art, mostly NaruSasu but a few sketchy arts of other subjects. Y
Yin&Yang -- Naruto, Bleach, etc. A lot of art; the style is rather sketchy, but it's good nonetheless.
032 -- Naruto etc. Another adorable pixel art site. Tons of KakaIru, though. C, Y
avoid -- Naruto etc. Some very pretty art, mostly of Naruto. Beware the KakaNaru and the excess of naked-little-boy-Naruto--but the rest of the art makes up for it. C, Y
shi-ki -- Bleach, DGM, etc. A bunch of excellent art; the Bleach side has a bit of a lean towards GinIzuru. Y
Marge -- DGM. Quite a bit of good (and often cracked) art. Y, WTF
sackcloth and ashes -- Naruto etc. Some absolutely amazing art. More Gaara than anything else, but also some Itachi art and a bit of other stuff.
Wicked Smile -- Naruto etc. A lot of art with an unusual amount of the Sand trio, particularly Gaara and Kankurou.
Kuragedan -- Naruto. Some exceedingly cute art of the Fourth Hokage, often with Jiraiya or tiny Kakashi. C
Seiren -- Naruto, Bleach, etc. Some very nice fanart, on the Naruto side mostly NejiHina and TemaShika, but some NaruHina as well; a lot of ShunsuiNanao on the Bleach side. The quality of the art varies somewhat, but some is very pretty and definitely worth a look. C
Sacrifer -- Naruto. Best crack-chibis ever of Orochimaru and Anko. Not lacking in other Sound characters as well, plus a few others. There's even a section of photographs of clay dolls done in the style of the chibis. C, WTF
Reimyou -- Naruto. Notably mostly for sheer crack. Mostly KakaSasu, although less pedotastic than most Japanese fanart for the pairing is. Also a bunch of terribly cute pixel-art comics. Y, WTF, C
Engawaken -- Naruto. Several excellent Sasuke arts and some good NaruSasu. Y
Magaru -- Naruto, DGM, etc. Very striking art with exceptionally vivid colors. Not all that much of it, but worth a look for what there is.
C-three -- Naruto etc. Includes some small but very pretty Naruto arts. WTF
Moyabo -- FMA. Full of crack (including the horror that is Hohenheim/Ed), but also has some excellent arts. Y, WTF
sui-sui -- Naruto. Plenty of cuteness, especially of the Yondaime and Naruto variety. Y, WTF, C
viento -- Naruto, Bleach, etc. More adorable pixel icons. Some particularly cute animated ones. C
BPM -- Naruto etc. Some very adorable art of Kakashi in particular. Also has some KakaIru, though. Y, C
Nightflight -- FFVII. Some very lovely fanarts. Mostly Cloud, Sephiroth, and Sephiroth/Cloud. Y
Crusade -- Naruto etc. Some cute arts, particularly of Team 10, in a peculiarly One Piece style. Unsurprisingly, also includes One Piece arts. C
M*H -- Naruto etc. Tons of sketchy but interesting arts.
AG Biscuit -- FMA. Cute arts, although sadly not that many so far. Hints of Roy/Ed, but nothing explicit.
K-flower -- SO3 etc. Huge stash of SO3 hentai if you're into that sort of thing; some non-porn as well. A little hard to navigate, but the art can be quite good. Y, H
CCC -- FMA etc. Rather hard to navigate, but has some nice (if sketchy) arts.
Zero Area -- FMA, Naruto, etc. Difficult to navigate (the main illustration page is here), but has some nice arts.
Benevolence -- FMA, Naruto, etc. The style's kind of weird, but there are some nice arts here.
Black Rush 57 -- Naruto. Some very darling arts, especially of Team 7. C
Aluga -- Naruto. Rather artsy and very pretty arts, with a focus on the characters of Team 7.
Siosai -- Naruto etc. Much cuteness and silliness, with some special crack reserved for the Akatsuki. C, WTF
Digital Scoop -- Bleach, DGM. Excellent arts, very clean and professional, plus quite a few more sketchy works. Y
Zen -- FMA, DGM. Very pretty arts, despite a distinct Roy/Ed tendency. Y
Min'Ss -- DGM etc. Much cuteness, particularly of Allen. Y
Black Joke Company -- DGM. Tons of insane comics with a focus on Komui. Y, WTF
W-mania -- DGM etc. Rather difficult to navigate, but often worth it.
seil -- DGM etc. Mostly Kanda/Allen, but lovely arts all the same. Y
Ishiya -- Naruto, Bleach, etc. Some inventive and gorgeous arts, but beware the odd slash. Also be prepared for wackiness if you venture into the hentai section. Y, WTF, H
Beehive -- Naruto. Mostly KakaIru, but also some cute general art. Y
Samurai Soul -- FMA, Naruto, Bleach, etc. A variety of cute and attractive arts.
Raindrop -- Naruto, FMA, etc. The quality of the art here isn't amazing, but the sheer cuteness sometimes makes up for that. C
UN Fanta -- Bleach etc. A number of precious Hitsugaya and Hinamori images. C
ARTOHOLIC -- Bleach, Naruto, etc. emlan's art site. Has a separate Bleach section with lots of cuteness and craziness. Y, WTF, C
arbor -- Bleach, FMA, etc. Primarily halcyonjazz's art site for now, although she shares the site. Some very awesome art here.
Mittinatta -- Naruto etc. croaky's site. Quite a large amount of excellent art, both fanart and original. Some of the prettiest Jiraiya art in E-fandom. Y
Mette's art -- Naruto etc. Also has a lot of InuYasha art. The Naruto side has a focus on Hinata. Very pretty art. nursemette's site.
Portfolio@Megaten -- FFX, Naruto, etc. Also Suikoden and some other video games. Some very nice art.
Somewhere-Nowhere -- FMA. Hime D. is the great Big Name Fan of FMA fandom. It's not all hype, though; her art is excellent. Y
Wratbox -- Naruto etc. Awesome arts; some hilarious, some just plain excellent.
Forksoul -- Naruto etc. A variety of excellent and inventive arts.
This post will be updated as I find more hot fanarts.