Any good onboard camaeras out there?

The mass transit bus I drove a while back had several cameras mounted inside for the passengers' safety. I was wondering if there is any thing similar used in the trucking industry. Maybe 1 camera facing out the windsheild. 2 more on each of the rear view mirrors. Possibly a 4th aimed at the dashboard. I'm thinking more of a CYA for the driver than a "Big Brother" scenario.

I'm asking as I would like to mount a similar system in my motorhome. I travel throughout the country on a regular basis. I still have the same problems in it as I did in a semi. 4 wheelers passing me only to slow down, cutting me off, exiting from the left lane. I'm sure you know what I'm talking about.

Ricky