In what sometimes feels like a past life after a heavy day dealing with botnets, I remember fondly many of the covert and physical penetration tests I've worked on or had teams engaged in.
Depending upon the goals of the penetration test, things like installing physical keyloggers on the receptionists computer (doing this surreptitiously while engaged in conversation with the receptionist - hands dangling down the back of the computer...) in order to capture emails and physical door entry codes, dropping a little wireless Compaq/HP iPaq in the plant-pot for a day of wireless sniffing etc., dropping "malware" infected USB keys in the office car park in the morning (waiting for the "finders" to check them out on their office computer by lunchtime) and pretending to be official fire extinguisher inspectors and getting access (and a little alone-time) in their server farm.
Anyhow, today I spotted an interesting gadget that would have been pretty helpful on many of these physical engagements - The PlugBot. It's a wireless PC inside what looks like a plug adapter.
If you're not a penetration tester - perhaps you should read about it anyway. Something to "keep an eye on" within your own organization then.