Musical Tesla Coil

[Ephraim]

http://www.youtube.com/watch?v=cOkTrqTd0hw

This is one of the most interesting applications of technology that I've ever seen.  They go into the principles of operation in the video and I'd butcher them if I tried to summarize them here.  I'd never really thought about it, but apparently if you have a spark flickering at a frequency within the range of human hearing, it'll actually generate a tone at that frequency.  I'm just floored by how cool this is.