Today in The Age newspaper Danny Katz referred to a theremin. Actually, he mentioned a Dr Who theremin.
I didn't have the least idea what it would be - turns out it's a musical instrument. Aha, so that's how they made that weird sound in the Dr Who theme.
Here's a guy having fun trying to play the theremin. Amazingly, you don't touch it to produce the music.
The story of the inventor is interesting, too. He was a Russian who went to the US but was forcibly repatriated to the USSR in 1938, put in a prison camp for some time and is said to have subsequently worked for the KGB. Maybe one of these days we'll be watching a film based on his life.
Here's a page of information about the theremin and its inventor. And here's a musician playing Ave Maria.
Oh, by the way, the theremin was played in the best sci-fi film ever made - of course, I refer to the 1951 film, The Day the Earth Stood Still.