They call the website "the social music revolution."
What is Last FM?

Answer:
Last.fm is a service that keeps track of what music you listen to, and then produces a large number of features personalised to you.

You can use Last.fm to listen to music, find out about artists you may like, other people with similar music taste, gigs in your local area, charts and quilts for your personal site, as well as much more.

...and I'm addicted! This is the place where I find all my concerts that are coming to the Seattle area and listen to the bands that are similar to my favorite band XTC.

Check it out--find your friends on the site and make fun of their musical tastes.
If anything, make fun of me here!