This is great because you can use any object to put it on there, and it will react differently.
The Reactable is even more interesting though. The visualization of the oscillation adds a level of complexity to designing it, though it simplifies the interaction with people. I find most of the sounds in this demonstration annoying though, I'm not much of a fan of trance anymore. I appreciate the creation of technology from concept though. Here is a slightly better video of the Reactable in action.