Last.fm

how does this works? it looks at how many times you played stuff at your itunes?

Its not only with iTunes, you can do it with "Windowns Media Player", "Foobar2000" and another players.
You only need to show the LastFM, what for player you are using...
When you listen something with your iPod too!

Then the LastFM show, how many times you did listen and what is your favorits bands.

:)