The Album Cloud
Andrew Hitchock uses the MusicMobs web services API to find out what your favorite albums are (based upon playcounts), and builds an album cloud using the album covers. The size of the album cover is proportional to the amount of play that album gets. Cool idea ... and a great way of showing what cool things people can do with an open API. MusicMobs does a great job of providing access to their data through their web services API.
Here's my current album cloud:
And you can listen to a 20 second signature version of my music collection here: Paul's Itunes Signature