User Submitted Backgrounds

[Petie]

While I agree that it would be cool, it's actually a lot more complicated than it seems. The background is controlled via an external stylesheet and looks for a file called background.png. When we update it, we just overwrite the existing background.

I do agree that archiving them couldn't hurt so I updated the background script to save a copy of the current background when uploading a new one but making that dynamically select-able would require more work than it's currently worth.