isight
I have played with using my JVC DV cam in place of a iSight camera, it worked great, I have a friend that was doing the same with his cannon camcorder at another location, we both plugged in and it just worked with iChat, also played with Yahoo chat and worked well too, the lag was very good, the audio was a little echo'y, so a headset mic setup might be the way to go, but he uses an Airport and I use a Linksys wireless router and neither of us did any set up... check out other stumbles I have run into on my switch over to the mac world on my blog..
D