I've got the downloader client working (windows only for now, my apologies mac ppl). It's pretty sweet. It's a little program that can automatically pull images from any module on this site, preview them, convert it to a bmp, and set your background to it. You can either keep manually shuffling through until you find something you like or you can set it to download at a set time increment.
This all assumes you have a broadband connection, however. Modem people may have to stick with manual downloading.
The final version will allow downloads of 3 sizes: 1100x825 (for 1200x960, 1200x1024, and higher), 900x675 (for 1024x768), and 700x525 (for 800x600). All you need to do is upload one large image and we'll do all the work resizing it. The backgrounds are smaller than their target desktops so that the text at the bottom isn't obscured by the start menu.
Text?
Yes, text. Each uploaded cel will have a "frame" attached to it describing the cel, its origin (show/year/episode/etc.), and a link back to your site. It's sort of a museum display title card. The frames are very plain and intended to showcase the art itself.
Client download available soon. Still have a ways to go, just wanted to show off the prototype.
Here's what it'll look like. Don't mind the factually incorrect text, I was just messing around.
http://www.rubberslug.com/misc/bgtest2.jpg
Alternate, but I like the one above better.
http://www.rubberslug.com/misc/bgtest1.jpg
Comments and criticism welcome as I work on this and other things on the site today. Cheers.