I think I'm less cranky and less prone to being angry on the road. Oddly enough, I don't drive. When I'm walking, I get pedestrian rage, but it doesn't happen on the bike.

I think I'm just more aware that I'm going faster than I am when I'm walking, I need all my wits about me and a cool head, and I don't waste any processing time to anger. If there's a shoddy driver on the road, and I have a near miss or something (which, honestly, I haven't had -- the worst I've had are people parked in the bike lane, and having to stop behind them and wait for traffic to clear before I try to pass), then when it's over it's over. I stop thinking about it and keep going.