I have been looking for a live video service, and I think that Ustream.tv is the right one. Here are a few of their features: Live Broadcast (obviously), record your broadcast for playback later, put text on the video, put video on the video (choose any video from youtube... and it can be picture-in-picture or you can make it take up the full broadcast screen), you can poll the audience, you can embed the video on another site (like here), and you can even password protect the page so that not just anyone can see it.
There are several other features, but I don't have time to get into them all. Check out Ustream.tv and let me know what you think.
You can also check out my "channel" by clicking here. If you're lucky, I might be broadcasting when you check it. If I am not currently broadcasting, you could always click the follow button and it will let you know the next time I schedule a "show."