I plopped down $300 US and ordered a handheld cell phone jammer from the U.K.(Illegal in U.S.)

Worth every penny when you get that a$$hole who thinks his phone conversation needs to be heard throughout the restaurant, coffee shop, post office or wherever. The satisfaction of shutting down a load mouth is indescribable , as you watch them fiddle with their phones and say "HELLO, HELLO". When they realize they aren't getting any signal, they usually walk a good distance away out of my jammer's reach and out of earshot to try to call again.

Note: I don't actually take it with my on the plane, cause I wouldn't want to have to explain to TSA what it was (looks like a cell phone), so I just check it and carry it around with me when I get to my destination

http://www.globalgadgetuk.com/Personal.htm