I agree very much on the filtering aspect of the stream. For instance, I have a problem with my RSS feeds: there's just too many of them and it takes a long time to check them all. Of course, you could go all Zenhabits here, but in the end, people are lazy. If you can somehow rank/filter the incoming info, you're on to something. Unfortunately, that's also the hard part, because just filtering by keywords (like feedrinser) is a quite crude solution, and you could easily miss out on interesting stuff.