This was just too cool to not post. :)
Using GPS and the already-in-place cellphone network, Direct Electronic’s Viper car tracking system allows users to “call” their car to do anything from warm up the engine to see if it has left a predetermined area. You can also set it up so it’ll send warnings if it has driven above a particular speed, has left a specific area (like if you want to make sure your wily teenager is only taking the car to school and back). you don’t trust the person driving the car), or you can just check where the car is and at what speed it is driving. This paranoia device will set you back $699, and can be coupled with other devices that will allow you to lock doors or shut off the engine if you want to spend a little more.