Bottom line to me is that being out in a boat is very much like being in the car... Watch out for the other guy, expect that he/she will not be paying attention, and drive/ride defensively.
Of course when it gets really crazy out there, and you seem like you are totally surrounded by idiots, it may be best to sit down, put your head between your knees, and repeat after me "Our Father..."
One thing that has always amazed me is that virtually every boat has the steering on the starboard side of the boat. It has been pointed out that the normal passing of two boats bow to bow would be to pass port to port. Why not be passing starboard to starboard, giving each operator an even better look at the other boat????? Just a thought. Probably goes back to driving a car and having traffic going the other way pass to your left.