Think no one can eavesdrop on your wired keyboard? Think again.
http://hackaday.com/2008/10/20/eaves...ds-wirelessly/
"Every time you press a key on your keyboard, a small burst of electromagnetic radiation is let out. This radiation can be captured and decoded. Though it only affects some models, this is pretty serious. They tested 11 different keyboards and they were all vulnerable to at least one of the four methods of attack. Tests have shown that the data can be read through walls and up to 65 feet away. That is pretty scary stuff. Someone could be setting up in the apartment or office right next to yours to listen to every keystroke you type. "
The article contains two videos of it being done.
Of course stuff like this has been going on since computers have been around. It first came into public view back in 1985 when a Dutch programmer by the name Wim van Eck published a paper and a proof of concept on how to eavesdrop on the electromagnetic emissions of a CRT monitor; and then reverse engineer those emissions into an image.
Oh and the NSA has been researching this stuff themselves under the codename
TEMPEST since at least the 60s.