So this is kind of cool. The iTunes Signature Maker will analyze your iTunes library and make a short sound file merging together parts of various representative songs, choosing a set number of them by play count, or rating, or other options. It actually comes out with some pretty interesting stuff. This is my favorite result from my iTunes library so far. For the options on this one, I used 40 songs, chosen by play count, five second clips, up to five overlapping at once. I thought the overlapping might be too much, but I actually kind of like the density of sound it creates. Another version has 30 songs, with four second clips, and no more than two overlapping at once. How many of the separate songs can you recognize?
Last.fm should totally integrate something like this with user profiles.
(Link via Lifehacker.)