Laser Microphone
I completed this project I think in March. You bounce a normal laser beam off of a reflective object, like a window, and back into a receiving unit. When noise is made near the window, the window will vibrate. The light will then move in conjunction with the vbrations of the window. The receiving unit can take those subtle changes in light and convert them back into sound. This device would most likely be used for eavesdropping. I still have to take some pictures or video or something and put them up here. I also have a sound recording I will upload at some point.