I like the advice of smiling and waving. It doesn't happen often but I think it's funny when someone is flipping me off and I just smile and wave back. It's like the frustration intensifies for the person.

Last summer this guy in a new Yukon knowingly cut me off so that I had to slam on the brakes to avoid contact. I got in the left hand lane and my passenger gave him a look of "what gives." He then proceeded to do the same thing again. This time I let him hit me (I was in my Sable). Nice dent in the Yukon and fortunately only a minor scrape in my beater. He drove off laughing. I called the police but since there was really no noticeable damage it wasn't worth a police report.

Truly the best but most difficult thing to do is keep your hands on the wheel and avoid eye contact. I have two kids now and altercations just aren't worth it. Nothing positive ever comes out of them.