Picked up a cheap Kensington Web Cam for $10 the other day. The Kensignton drivers are for MacOS 9, but haven’t been updated for MacOS X.
I found this great open source solution that I think works better than the original drivers.
It works great with my Kensington VideoCAM PC Camera Model #67014
Took some cool time lapse videos of the street out side my place over the course of a couple hours. You could see the shadows move and water evaporate from the sidewalk.
I tried hooking it up to take some shots of the night sky (the original reason I bought the camera) but it seems to be only good in a bright situation. Maybe through a telescope.