I'm putting all of the desktop backgrounds onto GitHub so I can see how they change over time as I find new ones, and learn to hate older ones. It isn't a small repository (120MB) but connection speeds are fast nowadays, so feel free to clone if you have similar tastes!
I run OSX and rotate my desktop every 15 minutes by adding the folder to System Preferences > Desktop & Screen Saver.
I cannot claim any of the fame due the people who created these wonderful images.
If you're looking for awesome stuff to use as your desktop background, check out -