As seen on Slashdot: a group of students at MIT have constructed a Disco Dance Floor, with over 1,500 LEDs and covering 128 square feet. Dance on it, and pressure sensors trigger some 4,000 colors. Jeez, I knew I shouldn't have gone to Sarah Lawrence;
these MIT folks don't mess around. Not only are the colored patterns
surprisingly sophisticated, but it interfaces with a Linux audio player
to work with the grooves.

So how do you build your own? Check the detailed construction details,
though consider what they learned: don't ever do this: "Don't try to
build a disco floor in your lounge; it will consume your life. Now
there's a lesson they don't teach in any class." Okay, fine, but when
they say "As far as we know, there is no mention on the internet of
anyone home brewing a dance floor of anywhere near this complexity,"
can't you hear the gauntlet falling? (Hey, stop looking at me! I'm just a keyboard player.)