For reference (Japanese fanart sites)

[annwyd]

Fanart Sites That Have Given Me Permission to Use Their Art
Kakure Wild
Nephrite (now closed)
Retonomiyako

Fanart Sites That Have Specifically Denied Permission
Aidma
Kumoji

Fanart Sites That Have Not Responded to My Requests
Reimyou
C-three
PochinokoPro
Mr. Randomness
candy*store
Probably some others that I've forgotten. Note to self: ask Keroyon for permission.

Fanart Sites That I Know Don't Give Permission
A2 (or so I've been told, although the text on the index page makes it seem like she's willing to give permission if asked)
Israk