Now that I'm working on projection mapping it was only a matter of time before this happened. Thanks to my brother for the inspiration, he mentioned that one of the other projection mapping examples looked a bit like a minecraft block. Once the idea popped into my head I had to give it a try.
There's a piezo element taped to the box and hooked up to an arduino. The arduino senses the physical impact with the piezo element and sends serial data to my PC. Processing picks up the serial signal and takes care of the projection and interaction (particles, etc).
As seen on: