Considering time and mileage on bicycle vs car/motorcycle/walking, I must say I get the least road rage while on bicycle. Especially considering I do slow traffic down sometimes, drivers have to wait for a gap to pass me on some roads etc.
When I start to feel a little bit bad about slowing down traffic (which I don't do often), I consider the miles and at least tens of minutes I go out of my way to stay on roads with bike paths, or use the MUP. I figure their 10-15 seconds of inconvenience isn't so bad. I'd like to make up some small magnets with a short pithy comment to the affect, that I could throw at or leave on cars when they get impatient.
ETA: Similar to this:
http://www.aerostich.com/sundry/shir...low-cards.html