Initially, to gather better info on aggressive motorists, now I've integrated chronicling the many changes along my commute routes that have happened over time.
Only a few cyclists have noticed my two bike mounted cams, and that was at a cycling forum a couple of years ago.
My front and rear cams are both Contour 1080Ps. (stealthy, and color match my black bike)
I don't feel safer, but I now ride with less frustration in knowing that certain number of motorists have far less of a chance in getting away with their aggressive behavior.
I use both my cams on a near daily basis.
Urban Commuter.