“Ustream.TV is the live interactive video broadcast platform that enables anyone with a camera and an Internet connection to quickly and easily broadcast to a global audience of unlimited size. In less than two minutes, anyone can become a broadcaster. All you need to stream is a computer, internet connection, a microphone and a webcam or video camera.”
Ideas for using UStream in the classroom:
http://www.ustream.tv/blog/2007/11/09/315/
