iTunes 9 – Genius mixes
I hadn’t heard much fanfare about iTunes 9 except with relation to the Home network sharing of music and the ability to rearrange the icons on your iPhone. In my opinion, a much bigger deal is the introduction of the Genius mixes.
The Genius feature was introduced in iTunes 8; if you’re not familiar with it, it takes a single song as input and attempts to create a playlist of similar songs. If you’ve used Pandora or Last FM before, it’s a similar thing. It usually works pretty well, though if you choose a rather eclectic song, it might not have enough matches to make much of a playlist.
Anyways, the Genius Mixes is the next logical step. It presents a few premade, dynamically updating mixes based on (as best I can tell) the genres of your music and their relative frequencies. For instance, there are 5 rock mixes offered in my iTunes, 1 electronic, and so on and so forth.
I really like this feature because I can choose a genre of music I’d like to listen to rather than having to pick a specific song with which to seed genius. Besides, I’m lazy and this saves me some exertion.