StepMania is an open source version of Dance Dance Revolution. I've done a few tools to work with it that I'm maintianing and releasing as under the MIT license.
Contained in jo.sm.dl. This is a Java tool that creates StepMania files from midi songs. Midi sounds like crap, but has the advantage that we know precisely where the beats and notes are. As there are a wide variety of MIDI files easily available, it is possible to create many StepMania files for popular songs of all varieties. The tool is provided for personal use. Do not post StepFiles created with this for public use if you do not own the rights to the songs.