Armed and dangerous at the airport
Suppose you like to have a pocketknife handy when you travel. Well, why wouldn't you? Useful things! A small blade, screwdrivers, maybe a bottle opener. But when you have to pass through security, they'll confiscate it. What to do?
Technology to the rescue! I found this at Brookstone's last week:
Open, it's a knife (serated and straight), a Phillips screwdriver, a wide flat screwdriver, a tiny eyeglasses screwdriver, and a bottle opener. Closed, it looks almost exactly like a key. Put it on your keychain with your other keys. When you get to security, toss your keychain in an outside pocket of your carry-on bag along with your other metal items -- watch, glasses, spare change, cellphone...it goes right through. And if they /did/ catch it, not a problem. Tell the security goons you forgot it was there and let it be confiscated; it's a mere $15 to replace!
Not that I personally would ever do such a thing, mind you...