I have a GoPro mount permanently attached to the top of all of my helmets. I don't get on the bike now without the camera running.
2 years ago I was run off the road by an inattentive driver (fractured 2 vertebrae). The guy took off, but I got his license plate number. No witnesses, no proof, no case. Now I record every second of my commute and have recorded some amazing (i.e. scary) footage. One time I captured a city bus running a red light and totaling a brand new Mustang. The driver lied through her teeth to the cops. My video made the case.
Anyway, I wear my camera for personal protection. I've discovered that there are cagers out there who are out to get us. I know, most motorcycle/car incidents are "I never saw the motorcycle..." but there are some who are out to get us. More than once I've had a cager pull up along side me and force me off the road...I get out of the way, only to have them pull up and do it again (clear intentional at this point). I simply point at my GoPro and they take off. I hate to think what they would've done without the camera.