Ustream.tv lets you broadcast any live event over the web using nothing more than a webcam.
You could use this free service to broadcast your band's concert, your high school's football game, your company's training session or just about anything else. All you need is a Ustream.tv account, a video camera (either a webcam or a camcorder that has webcam capabilities) and a broadband Internet connection (cellular modem cards are recommended for on-the-run notebook users).
You can schedule events, send out invites and archive broadcasts for later viewing. It's a pretty amazing service, though the Ustream.tv site doesn't do a particularly good job of explaining its features, nor does it offer much in the way of help. Still, this definitely has the makings of a Next Big Thing. What kinds of events would you broadcast?
Broadcast live events with Ustream.tv - Lifehacker