Banime- One of the oldest and most popular anime wallpaper websites that is still around after many years of activity. Managed by Bantam (who's also the owner and boss of AnimePaper), it's one of those website where you can find lots of 'old school' kind of wallpapers, done the way the ol' veterans like him do.
DA! Desktop Anime- Tama-Neko's anime wallpaper website has been providing quality wallpapers for 6 years non-stop and still continues steadily in its activity. Tama, mostly known around the communities for being a master veteran at vectoring (and also a sort of idol in my eyes, but don't tell her :P), has blessed us with some of most beautiful vector-based wallpapers. Great design taste, great composition skills, great... anything. Ok I'm done with the worshipping, go visit the website NOW.
Pixel Pusher- Website run by Dhias, co-adjuvated by Kyendo. Dhias is one hell of a talented artist and I wish I could paint like she does. D:
DigiTal Boing- Best Sci-fi themed wallpaper website. PERIOD. Sir-Boingal0t is actually an alien entity, born from the hands of god, who descended from the sci-fi heavens and decided to bless us poor mortals with his leet sci-fi scenic drawing skills. He makes a wallpaper once every planetary alignment, but it's damn worth to wait for it. Best quality guaranteed.
Animation Alliance- A wallpaper website that somehow serves as platform and host for other websites. Currently having only Highknees as active waller, the rest of the crew (5stringDNA, Xeno and Jay) being inactive. They still have a good amount of nice wallpapers stored.
OTAKUWORKS-
Again, a nice wallpaper website managed by one of the veterans of the anime wallpaper scene, and also a good friend and colleague of mine at AnimePaper, Dias. Being the animu specialist that he is, he likes to make 'simple' (if there can be such a thing like a 'simple' wallpaper) yet desktop-fitting wallpapers with a tad bit of old school flavour, while feeding AP's own mascot
Chuck(though I'm secretly planning to terminate Chuck and replace it with
Liru , but don't tell Dias about this

).
Phate- An other friend of mine, fellow countryman Phate, he's one of the few italian wallers around, and a skilled one! Could it be that we're all so damn leet (don't mind this uber-nationalistic comment, I might be possessed by insanity again)? Maybe. In the meanwhile, to find out if what I am saying is true or not, go visit his website.
Dragonrain- Jade, owner of this very nice and professional-looking website, is an other fine wallpaper maker and on top of that, an overall good designer (her website offers more than just wallpapers, in fact). Her most recent style of walling sort of resembles Grayserg's in some way, but with her own very personal flavour. Check it out!