Lots of 'em, but here's my closest call that didn't end in a wreck.
I was doing my normal 30 minute commute in the morning on the highway. It was a cool, wet morning. I'm in the left lane passing a coal truck while going around a left hand highway sweeper. He doesn't see me and quickly moves into my lane to get ahead of the car behind me. I barely manage to swerve into the tiny left shoulder. When I crossed the wet painted line, my rear tire lost traction for a second and I started sliding toward the truck. Fortunately, it regained traction a microsecond later, but it felt like an eternity. I was now riding in the left shoulder with a coal truck in my lane and a car close behind him (though he did rapidly slow down and give me room). I was riding the 250, so speeding out of the situation wasn't an option. I couldn't chop the throttle or brake because I was in a turn and didn't want to screw up my narrow line. I eased off the throttle until the truck was ahead of me. I then layed on the horn and gave him a long one finger wave. I was then stuck behind this asshole that just had to move quickly into the left lane for several miles as he meandered past the right lane traffic. I was red with anger. I wanted to pull the driver out and beat him unconscious. Of course, I didn't do anything except give him another one finger wave as I passed him (and wished a flat tire on him).