Ever consider having an aircraft black box in a car? If so, the Roadscan Drive Recorder might be of interest to you. The device continuously records video of your trip, and in case of an accident it keeps the 14 seconds before it and 6 seconds afterwards. This gives you a good record of the events of the mishap.
The unit mounts on your windshield or rearview mirror, and also records data such as acceleration, deceleration, date and time. The box hooks to a PC and easily downloads to your computer.
The Roadscan Drive Recorder sells for $299. While a really handy device for a car, the only thing missing is a quick erase button – just in case you are doing something that you don't want saved.