Anyone have a GoPro Hero3? If you then you already have an expensive car cam! The Hero 3 is suppose to be able to continuously record over and over on the same card so using it as a car cam works well. I've seen a few guys mod the cam so that you're able to connect the USB charger.
Those w/o a GoPro well.... Just get the one that Bob got. Cheap insurance!
The best part about these devices.... being able to relive the exact moment of pure action! lol Just make sure you're not the one in the "action" haha.