There are many <$200 car video camera / DVR gadgets on the market now (see 3 device below upper row). It would be great if radar detectors incorporated this feature since it's already up on our windshields and with GPS it could overlay our speed on it. Of course you may not want your speed recorded or video at all for spirited driving.
I currently have a diy setup behind my rear-view mirror for insurance purposes (see pics below lower row)
What do you guys think? Would you pay extra for this? I know I would!