Cheap Cell Phone Jammer

Link for more info: From Schneier on Security:

Only $166. It's the size of a cell phone, has a 5-10 meter range, and blocks GSM 850, 900, 1800, and 1900 MHz.I want one.

Pity they're illegal to use in the UK:

In the United States, United Kingdom, Australia and many other countries, blocking cell-phone services (as well as any other electronic transmissions) is against the law. In the United States, cell-phone jamming is covered under the Communications Act of 1934, which prohibits people from "willfully or maliciously interfering with the radio communications of any station licensed or authorized" to operate. In fact, the "manufacture, importation, sale or offer for sale, including advertising, of devices designed to block or jam wireless transmissions is prohibited" as well.