Now offered in Japan, and soon to be offered in other markets, Honda’s in-car camera captures video continuously on a non-stop loop. Once it detects sudden directional changes or heavy braking over .45g it saves 20 seconds of footage (12 seconds before and 8 seconds after activation). The driver can then play their greatest hits and nearest misses on the car’s navigation screen.
Similar systems that are already in use in Japanese taxi cabs have seen accidents reduced by 30 percent and insurance claims against taxi companies by more than 50 percent. Drivers also say it makes them more aware and cautious.
Source: Edmund’s Inside Line
There are devices for your car like this available in the U.S. as well. Check out the DRS-1100 - you can order online or find in NYC at J&R.
http://youtube.com/watch?v=LXl8VvFyxp0