I threw a (much more limited) version of a "desktop" website together in about a couple of hours.

http://xgpu.net/ is about an ongoing project for an external gpu for the Atari range of 16-bit (and actually I even have plans to make it work on the 8-bit range) computers. It's somewhat in limbo at the moment because I just moved continent and most of my stuff is on a ship in the Atlantic. Once that arrives, and we start to settle in, I'll get back to it.