Not sure how many of you have tried Genius yet on your iTunes/iPod. It rocks! Big time!
When I first installed it I was kind of annoyed by the MASSIVE iTunes upsell that is off on the side. I almost didn't get over it but then I started playing with it and figured it out. You select a song from inside your library and then click the Genius button. iTunes then returns a playlist of songs that are sort of like that song or at least seem to make sense to me.
Picture this, you head out on a run and are listening to Metallica and all of a sudden a mile into the run your ipod set to shuffle starts playing Dashboard Confessional's Screaming Infidelities. Buzzkill right?
Genius pulls together a bunch of songs into an on the fly list. For example I just selected Mastodon's Colony of Birchmen and I get back tracks from A Killswitch Engage, It Dies Today, Metallica and Black Flag. Proper running music. Nothing emo. The part I especially like about this is that I of course can make a playlist of all the songs I know but Genius actually picks a variety of songs including a bunch I have never played or listened to. True music discovery.
That is as long as you are part of the iTunes infrastructure. I have 6 Tool CDs ripped into my library and I was excited to get some playlists based on songs like Eulogy, Pushit and Sober. No dice. Not on this software. I am not sure if this is a technical limitation of not having the tracks in iTunes or a policy retribution but I always find the Tool vs. digital standoff pretty funny. And since I love Tool, I can respect that.