iChat AV by Apple and have been very excited about the quality of the audio and the video. It has been the best that we have used so far. The iChat software is free for Mac OS computers. It is compatible with AOL's AIM video conferencing running on Windows computers. We have used this software since 2004

In 2006 we used Meeting Plaza with our friends in Japan. This system worked well and allowed the Japanese participants to control a web browser on our side so they could share their project with us. We used their free trial version. It is Windows only at this time.

Most of these systems are relatively inexpensive and with a fast Internet connection they can work well. They are frequently designed for individuals sitting at computers so when you are trying to connect people in classrooms or theaters some creativity is required. The sound can be an especially tricky issue, both the microphones and the speakers.

Pros:
Cheap Cameras, like this old one we used three years ago
(color cameras are available for $100 - $150 US)
Some software is free. (NetMeeting, Cornell version of CU-SeeMe)
With a fast connection it can be very good.

Cons:
Uses an internet connection
Connection speed VERY important
Slow connection speeds mean slow frame rates and poor image quality.
We have experienced problems with computer network firewalls (security systems).