[adrianpike]

I built a fun hack back in college that used a laser microphone to listen to keypresses - the timing and sound of which is relatively straightforward to extract letter pairing heuristics from, and from that, given some time, you can build pretty strong guesses on people's passwords.

The next step I was going to take it was to use to microphones on different windowpanes and be able to triangulate multiple keyboards in a room - never quite got there because my DSP skills were garbage, but it's in the back of the mind someday to pick back up if I ever take a sabbatical.