If you are any way into music and use any semi-popular MP3 player (software-based), you should check out Last.fm! You install a little plugin onto your PC or Mac and it collects song information from your MP3 player and puts it into a database. So now you can see just how many times you listened to Jimmy Eat World – Sweetness and what albums you listen to are the least popular.
Oh and did I mention profiles? Yes you can add friends and find friends with similar tastes in music. They also allow you to check out new music with the Last.fm player – a piece of software that plays songs like a radio based on your musical tastes. You can even have RSS feeds of your last-played tracks. I highly recommend checking it out if you’re into music at all. You can view the last 10 songs I’ve listened to below.