From Split Video Capture Driver:
SplitCamera is a virtual video clone and video capture driver for connecting several applications to a single video capture source. Usually, if you have a Web camera connected to your computer, you cannot use it in more than one application at the same time, and there is no standard Windows options that makes it possible. SplitCam driver allows you to easily multiply your Web camera video in any conferencing software like ICQ, Yahoo, MSN Messenger, or whatever... and to broadcast it to many users at a time. With SplitCam you can connect up to 64 clients to a single video source.