Last.fm
Last.fm is a site that records your music playing habits with a plugin for your media player. Then with this information it generates charts of you most listen artists and songs. What it also does is provide music recommendations based on things that your musical neighbours listen to but you do not listen to. Another new feature is that is will recommend gigs that you should go to based on the artists that you listen to.
Links
http://www.last.fm/ http://www.last.fm/music/Shihad/ - Shihad's information on Last.fm