Kegi. This has excellent fanart. I'm not sure what kind of coupling is here...
Polypterus. Great Yu-gi-oh art site. Seto x Yami site
White Board. This is a good place for nice, 3D-looking, pictures. This is where I got my diamond leaves for my icons.
Anime sites (by show)
The Real Folk Blues. It's the ultimate source for anything Cowboy Bebop!