It turns music into gigantic sparks and, more fabulously, into music. A recent project called the Open Spark Project had musicians submit their music to The Tesla Orchestra, and with the wonders of software, it translated the melody into sparks into songs using giant Tesla Coils.
Gregg Gillis, also known as Girl Talk, submitted his music (which is actually other people's music cut up and mashed up) to the Open Spark Project.
The Tesla Orchestra/YouTube
Take a look and listen to something fairly amazing.