You may have noticed that over the course of the Brony Community's existence, there have been a ton of super high quality pictures more than qualified to awesome up your desktop background. Maybe you found one once and stuck with it through thick and thin. Maybe you're like me and switched so many times that eventually you just broke down and set them all to auto-cycle. But keeping track of all the little buggers is a very tricky task at this point.
Cue a bright-eyed, highly motivated pony by the name of Sigma90. He is currently undertaking a huge project to compile as many wallpaper quality images as possible into a single document. They've even been organized by resolution, and cataloged for artist, and image title. There's currently 42 pictures gathered, with another 55 in queue (plus a couple links to pre-existing galleries). Available in google doc and published doc flavors, for those times when you've got to have pony but are running afoul of that 50-man limit. Enjoy perusing!
Wallpaper Compilation (original doc)
Wallpaper Compilation (published doc)