Like old man said, this could be useful for locating where your kid is on a Friday night. But to spy on your spouse like that is just...wrong. If you distrust your spouse so much that you have to track his or her car 24/7, then maybe you shouldn't be in a relationship, you should be sent to a therapist. Of course there are useful things you could do with this, like tracking a stalker, cheating spouse, known felon's, and, probably the most useful of all, your kid.

Used the right way, this could be very useful