Yesterday our sister site Lifehacker posted a collection of eye-popping desktop wallpapers they found, and it is too good not to share over here.
I've had the same picture of the Pyramid Peaks in Colorado on my desktop since 2003. If your background's getting a little stale, too, certainly one of these will do the trick.
Lifehacker two weeks ago also posted some killer retro-gaming wallpapers (God, how I want the one with Asshole Dog snickering at me) but the flood of traffic killed Desktop Gaming's bandwidth. So keep an eye on that URL when it comes back up, it may have some good stuff. Just, you know, go there quietly, and in an orderly fashion.