Before Twitter, Friendfeed or Facebook even thought about real-time streams, Digg was already doing it with Bigspy. While I’m a huge fan of Bigspy, the problem is that it hasn’t had any development since it was launched. I think it’s time new features were added to make it even more useful.
If you haven’t seen Digg’s Bigspy before, then check it out – http://labs.digg.com/bigspy