On first pass it sounds like del.icio.us but with a way better interface. Everything is drag and drop. Visual easy to use design. It's a really great way to organize and sync bookmarks. Sharing a view is a bit clunky on first pass but once you figure it out (click on pencil by tab) it's a really great way to share sites with a group of friends or to make a bunch of site viewable to public (xerpi and non-xerpi users). Being able to share how you organize your sites is a big differentiator from other sites. The clunky part is sorting out friends. Once you add friends you can assign them viewer or editor rights. It's really a witty way group manage a view of links. Overall a bookmarking site that takes online bookmarking to the next level.