just for the case somebody's looking for a cheap webcam which is easy to install under gentoox:
i got myself the twinklecam pro (mind the pro!) which i found plenty of them on ebay for about 20 bucks. it provides 640x480 and i'm very satisfied with it.
you only need to "emerge camsource" and "install" the drivers (use v2.27) from:
http://alpha.dyndns.org/ov511/
and camera is up and running.
never thought it could be that easy:-)