I understand why cyclists get angry when cars get too close but screaming abuse at them or bashing mirrors solves nothing and only adds to the problem. Occasionally a motorist might be cowered by these tactics but more likely they will be infuriated and have even less respect in the future.
A classic example of this is the thread here in the advocacy safety sub-forum where the agro cyclist attacks a woman's car and she proceeds to run over him. To me that's like going up to a Grizzly bear and bashing it with a stick because it happened to wander onto the trail I was riding.
I feel strongly about all this because it effects me personally. I have to ride the same roads as these cockheads who go around aggravating drivers and turning their attitudes negative to ALL cyclists. The next time a car nearly pushes you off the road just take the license plate and make a statement to the police. The cops will have to act on it and the average driver's behavior in the future will a lot more bike aware once they know the police are watching them.