A real-life version of the tracking devices seen on detective shows, the Garmin GTU 10 lets you keep tabs on prized possessions. The waterproof GPS transmitter, which is roughly the size of a cigarette lighter and weighs 1.7 ounces, comes with a case, a carabiner ring, and an adhesive strip for attaching it to objects—a briefcase, say, or a dog collar. After registering the GTU on My.Garmin.com, you can create up to 10 "virtual fences" of any size, within the continental U.S. If the device enters or leaves one of those areas, Garmin will alert you by e-mail or text. You can also go online to see the gadget's most recent location and the last 10 points tracked. Cost: $200 for the device and one year of standard tracking, then $50 a year