If your looking for a great variety of desktop wallpapers, Pixel Girl Presents has the best around. So many to choose from and they showcase a ton of artists. You could even change it everyday if you want there's that many to choose from.
Pixel Girl also is a fabulous place to get iphone wallpapers, go here to download those. And there's even more...icons galore! Ok, I guess you just need to visit them to see all the stuff yourself.