This is a site with wery nice wallpapers/icons and a few teams for Windows and OS X.
The great thing is that you can chose resulotion of the wallpapers, so if yo have a very high resulotion on youre screen (I have 1600x1200 and it's usaly hard to find nice wallpapers in the right resulotion) there is no problem finding the right size.

InterfaceLIFT

Curently status
Wallpapers: 1,211
Mac OS X icons: 16,461 icons in 1,065 sets
Windows icons: 4,487 icons in 273 sets
Mac OS X themes: 148
Wind