Delayed: I broke one of the coils and am now looking for another harddrive to tear apart. After losing many other parts I decided to scrap this project until further notice.
Project is: ABANDONED
 WHY HELLO THERE! Its like.. a year and something later (August '07) and I'm finally trying to build this thing again. People like to use relays, I'm gonna do it with a dollar-store laser pointer, a harddrive case + voice coil + arm, and a speaker with a toothpick attached to it.
The basics: The speaker with the toothpick will be too loud to put music thru, so this will carry a 30Hz or 60Hz tone to modulate the visualization horizontally. The arm will be pumped with the actual audio (produces little noise) and will jerk the laser up and down at a high speed. a rubber band will hold the arm in place (it really likes to park). Both the arm and the speaker will be fitted with a small piece of a broken mirror, to reflect the laser to where i want it to go. I will dedicate an old laptop (one i didnt blow up.. check youtube for 'laptop explosion') to mix the audio and send it to the coil, as well as produce the tone for the speaker/toothpick deely. I already have the coil working perfectly, just need to build a small amp and do the thing with the speaker, which is at another house. All components are secured with hot glue. I dont have a glue gun so I melt it with a lighter. Excellent time saver.
While I did build it finally, and used it for a period of time, it was too fragile and needed too many on-the-fly adjustments to be practical. I will try again someday with servos or something.