Currently purchased and pre-loaded awaiting activation on my HDD is audiosurf. For those who don't know what the game is, it's a kind of puzzler/riding game that takes your musical MP3s, WMAs, etc. and builds a course out of it. It got some buzz when the beta was going around, but now the official release is here (and the steam version comes with the orange box soundtrack).
http://youtube.com/watch?v=k4S2WFWFu7A - Bohemian Rhapsody
http://youtube.com/watch?v=f3Tdut4pmIQ - Supermassive Black Hole