This one's just for fun...
For one: Radar detectors as optional equipment (built-in, as GPS is done now) on new vehicles.
It gets integrated into the entertainment system, so that if you are listening to the stereo, the stereo mutes if there is an alert (European cars already have this for traffic reporting - your radio goes silent and some guy tells you about a traffic alert).
It can also be integrated into the GPS - instead of V1 'arrows', it displays a graphic overlay onto the GPS showing you the radar origin.
Other future ideas?????