Phase (http://www.phasegame.com/) is a new music game for the iPod from Harmonix, the developers of Rock Band, Guitar Hero, Amplitude, Frequency, and Karaoke Revolution. It's probably most similar to their PS2 music games Amplitude and Frequency, although Guitar Hero and Rock Band follow a similar pattern of "notes" coming down a track for you to hit (and yeah, also like a ton of other rhythm games like Dance Dance Revolution, Beatmania, etc.)

What's cool about this game is that, although it comes with a few songs, it allows you to play the game with your own music. Basically you add the songs you want to be able to play in the game to a playlist in iTunes and it analyzes them to build the patterns for the various difficulty levels, and it works great. In the little bit that I've played so far (mostly just on the "medium" difficulty level) I've noticed that songs dominated by a syncopated rhythm tend to be more interesting to play than songs with a straighter rhythm. Anyway, I've had a lot of fun with it so far and thought some of you might be interested.