I don't view my car as a desirable theft target, so the likelihood of my buying something like this vehicle tracking key for security purposes is fairly low. Still I'm routinely fascinated by the ways we can use GPS devices to map out our lives. This USB keyfob vehicle tracking device is handy because it's not about the same size as a USB cell phone modem, attaches to any metallic part of your car using a magnet, and nails down your location within 2.5 meters. You don't need a computer connected to it to gather data, it works passively on AAA bateries until you connect it up for a data dump. Data collected is compatible with Google Earth, meaning you could easily make one of those Family Circus-style maps of your travels. If you've got teenagers, it might be a handy solution for keeping tabs on your car. If you drive for work, using a GPS to track your mileage would also be a convenient way to keep tabs on the driving you need to report either for company reimbursement or in your annual tax reporting to the IRS.
Apparently one of these units helped solve a murder case. You can see an unboxing of the device and details on the murder case here:
I don't view my car as a desirable theft target, so the likelihood of my buying something like this 