I've talked about the streaming P2P stuff, like TV Ants, etc, but I've recently found a site that will stream (or at least link to a stream) of all current live sports events.
I've been looking for the Arsenal football games online since I live in Australia and some aren't shown on TV here, and found a great site for all the Arsenal games with various streams (
http://goonerstreams.com/) but while I was there and one of the games weren't working I was given a link to
http://www.mixlivetv.com/and have used it a couple of times since.
I've never actually watched anything other than football matches on it, but there seems to be all kinds of things, American Football, Hockey, Basketball, Baseball, Rugby.
I think there aren't any links on right now because the games are either over or not going to start for a few hours. Anyway if you go to that site when the game is about to start you will see a link. I've found it very useful.
And for Billy & Tex - it has a streaming link to ManUn.tv and Chelsea.tv (you guys probably already have this).