GrooveThang is a quick and easy launcher for both Ultrastar (the PC clone of SingStar, a karaoke game that scores you based on how well you are singing) and Stepmania, a game like Dance Dance Revolution that challenges you to dance -or strike your keyboard/remote - in time with the music.
Later editions may end up scanning your Media Center for music to use, but at the moment you will have to get your OWN content. http://www.ddruk.com is great for Stepmania files, while a limited collection of Ultrastar files can be found from http://www.ultrastarstuff.com
If you could help me test it (there may be some volume issues, since I have to enable your microphone when you start Ultrastar), that would be great.
http://www.push-a-button.com.au/products/mce/GrooveThang.php
This installation includes Ultrastar, but you will need to download and install Stepmania yourself.
Author of 'EMUCenter' to play arcade classics 'MoreWithMyMusic' to sing with and normalize your Music, 'Yougle Vista' to watch YouTube, DivX & More and 'BlindTimer' to time your poker game.