Originally used by the KGB (as most everything was), it was a teeny tiny dart gun that could shoot over 250 feet. The CIA got a hold of it, but reports say that no agents actually used this little devise. Oh, and did I mention that it was tipped with poison?
No, this wasn't used to blow up a roomful of enemies (though, I suppose points in the plus column if it did.) It was actually used by British spies to protect documents that fell into the wrong hands. The carrier of the briefcase knew exactly how to open it. So, if it got into the hands of the enemy, the idea was they would open it up incorrectly and the entire thing would explode, destroying all of the sensitive information and, let's face it, probably the bad guy trying to open it up.
Cigarette Case Gun
When you're a spy, it's all about being able to conceal things. During WWII (which is when most of these things were invented), the Americans had a small, gold cigarette case for their spies, that shot not only bullets, but cyanide tipped bullets, ensuring that even if the spy missed the vital organs, the target would still die.
This little gadget was actually never put into production, but used to convince congress to err on the side of caution. It was a tiny (fake) olive that held a short range microphone, easily able to be placed in someone's martini glass and record their every word. After this, Congress really brought down some harsh bugging laws, making it much more difficult to record someone without their consent.
These are just a few spy gadgets that exist. If you're interested in more, check out the Spy Museum if you ever happen to be in the DC area. Have a favorite gadget? Real or fake, let us know! And stay stealthy.