Yahoo IMVery popular service that works pretty well and is fairly easy to install and use, however offers only small images
SkypeBecoming very popular, a combination webcam and phone service, free for basic use with pay options available for more features and ability to connect to non-Skype phone services
Tin Cam $19.00. My current preferred program. Works well, but some of the menus are a bit confusing. Will run multiple cameras on same computer. Streaming available.
VisionGS Pro $29.95 (Free limited feature version available) Will run multiple cameras on same computer. Streaming available. Difficult to understand much of the setup
booruWebcam Free, a simple program which works, mostly. There is a bug in version 2. If you have the preview window open and try to open the Options dialogue, the program may crash. Work around may help: Close the preview window at least 15 seconds before trying to open the Options dialogue. I have tried to contact the author about this, but have received no response.
KABcam $24.95 A fair program with lots of options. Website says it will handle multiple cameras and see the read me file, but there is no read me file included and nothing in the help file on this. Thumbnails and email sending available.
Fwink Free. Simple free program that seems to work nicely. Somewhat limited in configurations.
Willing Webcam $29.95-49.95 Many options available, but I found the coding to be inefficiently written. Ran slowly and difficult to understand many of the options.
Digi Watcher $39.00 Geared primarily for video surveillance use
YAWcam Free, asking for donations Simple but very flexible, lots of options, seems to run smoothly, written in Java, single camera only.
Programs I have not used, so I can not vouch for them. I may test them if I get board, and when time permits.