Guruger came up with a social networking idea of your music library along with a player for listening. How it works? Well it requires you to download a piece of software (1.5MB) which actually index your music collection and upload the index online at your profile. It's required to leave the Guruger music indexer open or running if you let others to listen to your music and playlists. Yes i know it might remind you about the social music revolution last.fm, they have a popular audio scrobber engine which tracks and indexes almost all media players. Other basic features of a social networking features are being included as example as Neighborhood, Friends, Private messaging, commenting and so on. It's a very new startup, so you might want to give it a test. Go ahead to their site, it's free.