I wrote an iPad app for New Year's Eve, so that people could just pick the music they wanted to hear. Based on the dance party in my living room that night, it worked quite well, so I polished it up and released it.
I'm using cocos2d and box2d for physics. The music comes from the built-in iPod library, so basically, it's a more fun, intuitive interface to the iPod.
Here's a teaser video.
You can download Tune Drop from the app store here:
http://itunes.apple.com/ca/app/tune-drop/id415138556?mt=8
And here are some promo codes for Tune Drop...
ENYPRMKN3YJL
634JNNMNLLME
AE7XFKA4XY6M
If you like the app, please write a review (there's a direct link in the help screen). If you run into any problems, please leave a comment here.