I decided to harvest a peizo buzzer off one of my many salvage boards to use while troubleshooting a new IR reflective breakout per Frits' description in Live Show #012. It works like a machine. I only fried one sensor (hasty connection straight to V+). Surface mount components are easy to replace though, thank The Maker. The video has everything but the sensor carnage.
Ahh, sound debugging \o/ I think I've entered my personal Golden Age of Robotics.