Jundo mentioned CamFrog which looks pretty good, but the server only runs on Windows (bleah) and although I can set one up, I can't actually connect to my own server. Plus the free version is pretty crippled.
I've been researching options all night but there's a real lack of decent video conferencing solutions that don't have a Fortune 500 price tag :P
This is free, Flash based (should work with almost any computer) and supports up to 16 people, give it a try:
This room for meeting & chatting: http://www.treeleaf.org/zendo/meeting-room.php
This room for zazen: http://www.treeleaf.org/zendo/sitting-room.php