Probes placed on the ground for the electric wiring can pick up these electromagnetic fluctuations, and they can be captured and translated into characters. The potential for this type of eavesdropping has been known for decades, and many experts believe spy agencies have refined techniques that make it practical. Andrea Barisani and Daniele Bianco, researchers for network security consultancy Inverse Path, are presenting their quick-and-dirty research on the topic at this year's Black Hat USA conference in the hopes of sparking more public research of these techniques.

3. Laptop eavesdropping via lasers: Bouncing lasers off laptops and capturing the vibrations made as keys are struck give attackers enough data to deduce what is being typed. Each key makes a unique set of vibrations different from any other. The space bar makes an even more unique set, Barisani and Bianco say.

Language analysis software can help determine which set of vibrations correspond to which key, and if the attacker knows the language being used, the message can be exposed, they say.

4. Commercial keyloggers: Early keyloggers were devices attached in-line with keyboards, but they advanced to software tools that grab keystrokes and store or send them to an attack server. have the software loaded on memory sticks that can dump the software on a computer and then be reinserted later to download the collected data.

5. Cell phones as remotely activated bugs: Software loaded onto certain models of cell phones can silence the ringers and cut off the light displays that would normally be triggered when calls are made to them. The caller can then listen in on conversations in the room where the phone is located.