The piqued my interest so I checked out the site. It's a service that tracks what you are listening to. It does this with plugins for iTunes, WMP, Winamp, etc. What's the point? Well:
*) It can tell you other people that listen to similar music (to make friends)
*) You can look at what they are listening to and find other bands they like which since your tastes are similar might be something you'll like
*) You can have it recommend stuff for you (it basically probably just looks at other people's lists for you )
Here's my list. Note that I just started using it today so I don't have enough info in there for it to recommend anything.
They even offer some XML and RSS based services so maybe I'll whip something up to display that info here. 😊