I visited the Frankfurter Musikmesse 2 weeks ago and played with the Yamaha TENORI-ON. I thought, it would be much nicer when the triggered notes would force a wavemap to oscillate. It took me just a few hours to implement. The sound generation is basically a polyphone synthesizer with a simple delay with a variing read-offset to make the tones vibrating in the end. I am already addicted for myself to the cute sequences it always generates.
Found via Beyond the Beyond.
(There is a great Tenori-On inspired iPhone app now available as well.)