I just don't let these people bother me anymore. Some of the posters in this thread are right, If they are honking at you, then they can see you and hopefully not hit you. I am still amazed about surviving two years as a bike messenger in the most dangerous american city to ride a bike in, Atlanta. Honking is the least a motorist can do to you. On too many occasions I have witnessed bikers with attitudes get run down by road enraged motorists. I remember on one rare occassion an angry motorist actually got out of his vehicle and beat a fellow messenger with his buddies and then left him bloodied and semi-conscious on the sidewalk.
On my ride to work yesterday, I was riding on my block where the posted speed limit is 25mph. As I was nearing a stopsign, an enraged woman in a red mazda protege came up alongside me at a high rate of spped only to slam to a stop a mere 15 feet later at the stop sign. She was yelling through her open window that she could have hit me and that I needed to get off the road! I proceeded to thank her for not hitting me and continued with my business. In retrospect, I could have pulled her out of her car by her hair and backed over her with that little red car but that was the old me. The old me was a person who carried canned food in my courier bag to lob at offending motorists and chase cars for blocks on end just to get my point across.
You just can't expect motorists to be sympathetic with cyclists, period. I spend more time now just avoiding conflict with them all together and hoping that I am seen on my long midnight ride home. If someone honks, I just let it slide and feel lucky that I was not side-swiped or worse.