Theremins

[xizoesira]

Check these out. Sets you back about ~$400. I'm thinking about a purchase.

http://en.wikipedia.org/wiki/Theremin
http://www.thereminworld.com/

Acid Mothers Temple used one last time I saw them live. Jimmy Page had one as well, would use it to simulate out of this world string bends.

[zhyla]

A friend and I are making one but we're really busy at work and he's getting married so it kind of got put on the back burner.

[EADG]

I really want to try one, but I don't imagine they're very common

[zhyla]

You can get them on ebay fairly cheap ($100-200), dunno if there's good and bad ones.

[We_Love_Lime]

Get the Moog one.
The Moog Etherwave?
I have it.
I like it alot.

[mutant!]

Theremins are hella difficult to play accurately. Loads of classical pieces that were written for the instrument eventually just got transcribed for ondes Martenot.