Bitshift

As a holiday present, Lady Ada has released her open-source cellphone/Bluetooth/portable phone/GPS/WiFi jammer. The site contains everything you need: Parts lists, parts sources, prices, schematics, firmware, PCB layout files, instructions for getting your boards etched professionally, links to theory, tools list, yadda yadda.

No more sitting through movies in the theatre while the teenagers three rows back yack the entire time! (NOTE: Operation of such a device is illegal. The jammer, not the teenager.)