Meet Pearltrees: Bookmarks with a social twist
A French Web site, called Pearltrees, is developing a Web service that is trying to bring a social networking element to bookmarking - but with the connections based on content instead of people. Think Facebook and Twitter mixed with one Amazon's recommendation system. You don't add friends in Pearltrees. Instead, you add links. As you come across something on the Internet that interests you, something that you might have otherwise bookmarked or tweet, you put it in your personal pearltree - which is really like a "main folder," that contain the links themselves, called "pearls." Here's the trick: if there are others on Pearltree who have also posted that same URL into one of their own pearltrees, you are now connected and can see their other links. The service, which is free, is still in alpha mode and has limited functionality and exposure. For now, it's a bit buggy but the concept is pretty solid.
Related: Pearl tree info