Two of us have been building hackerstream, a real-time UI for Hacker News that a dozen addicts have been using since March. This won't matter to you if you don't frequent HN, or even if you swing by just once a day. But try it out if you go to HN every couple of hours like I do. You'll see comments on all the stories on the entire HN frontpage as they stream in. You can slice and dice the stream by story or by author. You can even set it up to highlight, say, all comments by security guy Thomas Ptacek and all comments about today's silicon valley brouhaha. If you use Twitter the UI will seem familiar.
Is such a firehose useful? Is it too much of a good thing? I find I see more of HN for the same time investment, and I waste less time scanning stories I've already read. What's more, when I started using it I found my comments getting more votes and more responses. It turns out the biggest factor affecting responses is not how good my comment is but just how early it shows up on a story. By biasing my reading to be more timely I was giving my few comments improved odds of a response.