Compromising your keyboard by sniffing the EM radiation signature.

We found 4 different ways (including the Kuhn attack) to fully or partially recover keystrokes from wired keyboards at a distance up to 20 meters, even through walls. We tested 11 different wired keyboard models bought between 2001 and 2008 (PS/2, USB and laptop). They are all vulnerable to at least one of our 4 attacks.

Neal Stephenson did this in Cryptonomicon. Of course, fictional events are trumped by actual results.