I went through this a few weeks ago and got a QuickCam VC for videoconferincing.
Pro: cheap (C$80)
Con: low quality
If you want to videoconference, go with the cheapest you can find - it will do the trick, since videoconferencing doesn't really take advantage of a good camera's optics.
If you want to be able to do more, I hear the 3Com HomeConnect is a very good camera with superior low-light optics. It's sold in a PC box but drivers are on-line. The Kensington line for Macs seems to have gotten a lot of bad press, and don't know about the Kritter. They are coming out with FireWire cams, so the USB models might be on the way down in price.