I hope Stamped can get traction. The main idea is that you “stamp” things (restaurants, books, movies, music, software, etc.) that you like and would recommend to a friend. It feels great to use; has the right amount of think and feel.
But, then again, I think that about Virb and Rdio – both popular, but not near as much as they could/should be.
What separates Stamped from other similar sites/services is the simplicity. What makes it the same, though, is that it requires an active and working social graph in order to produce value.