I was tasked to setup a web cam on Linux. After looking around a bit on NewEgg, I was led to believe by one of the reviewers that Logitech QuickCam Communicate STX would work with Ubuntu 6.10 out-of-box. So, I got the web cam and plugged it in. My system only recognized a USB mic, no web cam. I went on-line searching for an answer. After dealing with various howto docs/forums on spca5xx and pwc drivers unsuccessfully, I came across this driver page, downloaded the driver, extracted the bundle,
sudo make install, plug-in the web-cam, ran camorama, and it WORKED!
If you already have a web cam or wish to buy a different one, see this list before you attempt to install the driver.
After getting the web cam to work, I set up Ekiga, a SIP/H.323 client, and got a SIP from ekiga.net. You can also get a SIP account from Free World Dialup (FWD), which provides similar service to Skype, with an added ability to connect to other networks. You can use this help page to setup Ekiga. If you would like to try other SIP clients, here are a few: SIP Communicator (Java, appears video is still in progress), FWD Communicator (Windows), NetMeeting (Windows, see here and here), and for more clients, see this list.
(Update) Here is another HowTo on a related topic.