I had the pleasure of playing with a Tenori-On this weekend. It has one of those magical interfaces that makes one immediately giggle with joy.
Here’s a great video of the Tenori-On’s creator doing a live performance (view full size here):
The appeal lies in the interactivity: by pressing the LED displays/buttons as it continually loops you directly interact with the music as it’s playing. As fun as this is now, I can’t help but yearn for the inevitable multi-touch display version to open up even more possibilities.