What is last.fm?

Well, that was the question that came to my mind while exploring my new music player name amaroK. So I checked it out and was surprised by the great idea behind this project! Why not tell the world what music you’re listening to? Generate statistics which artists seem to fit together? Check it out. My personal account is elmo2k3.
By the way: there are several plugins for many music players available that tell last.fm just what song you’re listening to at the moment. amaroK got this feature by default.