I have a fairly fast temper and often end up acting in the heat of the moment rather than using my brain.

What I think the best course of action is:

Ignore whatever the idiot is doing and STAY AWAY. Wait for him to pass. Take a different road. Get away from him because no matter who is wrong or right, he's in a huge metal bubble and you're on a bike with a piece of foam on your head. If the driver is acting dangerously to the point where I feel he's going to hurt someone...like driving under the influence...I will call the police.

What happens too often (I'm getting better):

I yell back, rely on being bald, stocky and with a goatee to intimidate whoever the idiot is (I pray no one calls my bluff, I'm NOT a fighter) and put myself in danger over nothing.