As a kid, riding with the traffic on my 20" single speed, I felt a rush of wind pass my ear. I looked up to see some idiot holding a pipe out of the window of a truck.
For the rest of my youth, I rode against traffic. Since cyclists are required to follow the traffic laws this is illegal, which is unfortunate, because the cyclist is putting his life in the hands of the drivers. Riding against traffic is tricky, however, when a driver is making a left turn - they are looking for oncoming traffic and won't see the cyclist riding against traffic until the last second, usually.
Recently, here in Summit County, Colorado, the letters-to-the-editor in the Summit Daily got a little heated over the issue of cyclists using roads versus bikepaths. There is a two-lane road over Dillon dam, in particular, that sparked debate. Anti-cyclists even went as far as to write that given the choice of a head on collision, taking a breath and slowing down or hitting a cyclist, they would hit the cyclist. Drivers felt that cyclists had no right to the roadway because there is a bikepath right next to it. When the newspaper ran a picture of the newly posted sign prohibiting cyclists from the roadway, you could see the bikepath in the background. The photo revealed why cyclists would use the roadway when a perfectly good bikepath ran alongside it - on the "bikepath" two pedestrians were walking, side-by-side, with a dog, taking up the whole bikepath.
I have ridden the exact same path many times and when approaching pedestrians, I yell out "hello" 20 yards, or so, in advance. One particular day, a woman with a particularly large posterior was walking alongside with her companion. When I yelled out "hello" she turned, looked at me and continued without making the slightest effort to move to the side. Needless to say, I made a very audible suggestion that involved characterizing her bundinghah as I rode past her.