I believe you can download countless songs for stepmania. I know my friend had remixes of madonna songs and such, on different skill levels. I don't see why there would be a lack of songs.

I know with DDR, you can set it to have a string of several songs in a row so there is no significant pause between songs and no stopping.

I was about to suggest Stepmania as well. :) And lots of the original DDR mixes are also available on it. If you download it, you may want to have a look at http://www.ddruk.com/ and other similar sites, where you can download plenty of mixes. It's what I've done, and the only cost was the pad itself. :)

i LOVE DDR. it's such an addicting game. good for a fun workout.

i love dancing to "Butterfly" and "Drop The Bomb" on regular mode.