Does this sensor create, actual usable voltage, and at what level?
I once used such piecoceramic senors for constructing drum-triggers for an electronic drumset.
Mine looked a bit different, but i suppose they work the same way.
The only thing about the voltage i know, is that the signal is a very short but eventually (referring to the mechanic deformation/vibration of the sensor) very high voltages.
But im sure theres a way to control the voltage anf make it arduino compatible.
Theres already a diy project called "MegaDrum" wich is a microcontroller based trigger-to-midi-converter.
Pizeo Arduino Information would be cool if anyone knows more...
You can mount those sensors everywhere and could do cool stuff with it. (Also the rockband drum controller contains piezos) So there would a be a wide range of applications...