Install iChatUSBCam

iUSBCam is an add-on for iChat which allows you to use a USB webcam for video conferencing.
It also enables Chat video conferencing on Macs which otherwise fall below Apple's system requirements for conferencing.
For example, with iUSBCam, you can use a Logitech QuickCam for video chat, or an iSight with a 500 MHz iBook.
More Features:
-Use most USB webcams with iChat.
-Videoconference on a computer that iChat does not support.
-Adjust camera settings like brightness and contrast.
-Use a DV camera on a G3.
-Adjust all iSight settings.
-Videoconference using your screen as a video source.
-Easily switch between available video sources.