I just discovered Ustream.tv last night as I was looking for an easy way to broadcast my ChickenCam. Perhaps discovered is the wrong word; I've known it existed, but never had a reason to use it before we picked up 6 Barred Rocks chicks from the local feed store and it seemed only natural to start blogging and streaming our adventures with them. However, as I explored the free service, I realized that this was a powerful resource for educators.
Not only can you broadcast live from any computer with a webcam, but you can also record your stream as I did with the ChickenCam video below.
In Ustream, you create a "show" to which you can begin broadcasting at any time. Just find an Internet-connected computer with a webcam, log into your account, and start broadcasting. You can create multiple shows, continuously broadcast, or set up recorded shows to appear in a YouTube-style list if your webcam is offline. Speaking of YouTube, you can send your recordings directly to YouTube as well.
While the service is free, it is ad-supported. An ad-free version called Watershed is available and comes with additional editing and API tools. While this would certainly be useful for something more formal or widely broadcast than a classroom or Ms. Gloor's own classroom chicken hatching project or university office hours.
A few ads are a small price to pay to make your classroom lectures and activities available live (or asynchronous) anytime, anywhere. If you haven't already, check out Ustream. There's a lot more to it than my ChickenCam.