EMI

Extraordinary Musical Instruments. Here's a few:

Continuum Keyboard on Wikipedia and Youtube

Eigenharp on Wikipedia and Youtube

Reactable on Wikipedia and Youtube

Double-Slided Controller on Youtube

Enjoy and feel free to add more!

Listen. I have enough trouble with six strings and a fingerboard

teddy

Did someone mention strings?

Ahhh. Joni

The double sided controller was the only one I liked

Huh, as much as it's interesting to see/hear, it was the only one I didn't really like... But the Continuum keyboard on the other hand, that's just a brilliant idea. And it can be used in so many ways. Had it been cheaper... ($5290.00 for the keyboard and $1870.00 (!!) for a dedicated stand, according to the producer's site)