Last.fm – Wow, I am impressed so far. Simple, I got an acct, downloaded the software, which automatically detected my winamp and media players and self-installed the necessary plugins to enable their scrobbling feature; retrieved the code for their blog widget for my personal scrobbling playlist chart, and posted it to my blogspot template – all in less than a ½ hour.
Now I finally have a central repository for my usage and listening preferences. And it doesn't try to rearrange my playlists and file storage schemes like iTunes! I just play the music and it phones home what I'm playing. And everyone benefits from knowing what I been listening to at any given instant (allegedly). Woo!