There was an interesting question posed in the New York Times today: "Would you let your insurance company electronically monitor your driving if you knew it might result in a discount?"
In plain terms, a black box in your car would monitor a bunch of different variables to determine what sort of risk factor you present (ultimately letting insurance companies know how much to charge you).
The box would be recording "not only how many miles [people] drive, but how they drive those miles." Other factors would include miles per year, acceleration/deceleration, how aggressively/defensively the car is driven, and where (if GPS-equipped).