I came across this awesome video today of Jared Ficklin and a Ruben's Tube that he setup. Basically, he uses fire to create sound visualizations.
[kml_flashembed movie="http://www.youtube.com/v/HpovwbPGEoo" height="350" width="425" /]
I met Jared at FlashForward in Austin a few months back when he was doing a lecture on sound visualizations in Flash. You may also recognize him from the very cool PBS show "Texas Ranch House".