This is an experimental set I did at Phog Lounge in Windsor, ON. I had several piezo discs attached to an Arduino which was interfaced with Max/MSP/Jitter and then sent MIDI information to Logic in order to trigger VSTs live.
The piezo sensors were used to trigger a sequencer that chooses notes based on pressure. I would also select the quantization (1/16, 1/8, 1/32, etc.) in order to trigger sounds. Because the piezos were attached to wood, they're reaction to vibration was unpredictable, responding to various vibration and pressure, making the result be more improvisational.