GPS petfinder (satellite tracker)
An obvious and excellent use for GPS, unfortunately only available in US right now.
GPS pet finder: When your pet roams outside the specific areas you've designated, you'll immediately receive a text message on your cell phone telling you exactly where your pet has gone. In fact, anytime you want to know where your pet is, just dial FOUND on your cell phone, and you'll get your pet's location instantly--and its environmental temperature.
â€¢ Locate your pet anytime with a simple cell phone call
â€¢ Monitors your pet's environmental temperature
â€¢ Water resistant, includes rechargeable batteries
â€¢ Never lose your pet again; uses GPS and cellular wireless technology
â€¢ Define a virtual fence and receive alerts when your pet strays outside it
It's a bit heavy, weighs a pound!