It's truly amazing what some people will try to carry on to a plane. Most of the knives, power tools, scissors, etc. are resold by the TSA at state-run stores like the one in Harrisburg, Pa.
CNNMoney's Aaron Smith holds a realistic metal replica of a World War II-era Schmeisser submachine gun that one clueless air traveler tried to board a plane with. Needless to say, the passenger was forced to leave it behind.