Bloglines launched their references feature last week. Its a link from an item you’re reading, to people who linked to that item. As the database starts to populate, I’ve found its all a great way to skim the high traffic, high popularity feeds (like thoses of major corporate media) for items of interest. Let the NYTimes, or BBC back up for a couple of days, and then skim down the list of 150 new items, looking for highly referenced articles.

As always, the best collaborative filtering works when its built on top of activities people are already doing for themselves.