It's a fun instrument. It was used in Messiaen's, Turangalīla-Symphonie, and is sometimes used as a substitute for the Theramin - which is somewhat related to the Ondes.
You also would have heard this on the Ghostbusters soundtrack.
This is a fantastic demonstration:
https://www.youtube.com/watch?v=Yy9UBjrUjwo
I believe Radiohead use one on In rainbows (forget the track name tho!)
This video is the best btw!
Actually using the favourite system here for the 1st time for this video