Diebitter: I have an idea for you. How about some sort of tracking system? You've heard about
http://www.wheresgeorge.com/ right? Or what about
http://www.bookcrossing.com/ They both track things that just move around freely, money and books. You could showcase your webdesign and database skills, but completely limit the project to whatever level is suitable for you. And since it's just for fun, no worries about maintaining it when you're tired of it.
Blarg:
http://www.homeagainid.com/
Registers all brands of microchips (there are about 20, by the way) and stores database online that you can check online or by calling. They charge about $15 per animal, but it's totally worth it.