Here is a "signature of the music I listen to", analysis of my iTunes playlist, based on 60 most listened tracks.
Generated by the sparse yet full operational "iTunes Signature Maker" by Jason Freeman. Nicely done.
Warning: The iTunes Signature Maker is a Java applet that you have to "trust". I don't know what else it may be doing so decide for yourself if you trust it or Jason Freeman. I'm thinking it's a safe bet but you never know. ;)