I've certainly had my share of motorist annoyances: getting buzzed, honked at, yelled at, taunted, etc. and a real near-miss or two. during my first few months on the bike, I came to see cars as The Enemy.
then, on a group ride, I noticed that our ride leader was going out of her way to wave and yell "thank you!" to cars that yielded, etc. since then, I've tried to implement the same. I even try to wave cars by when they are waiting but I think there's enough room.
the effects have been really something. not only am I less tense when riding, less likely to expect the worst, but I get the sense (perhaps naively) that motorists treat me a bit better than they used to. (yes, I'm a daily commuter and probably see some of the same people day after day.)
there is, sadly, much anti-motorist sentiment among cycling advocacy groups. I certainly understand that there are a few (very) bad apples out there, but treating drivers in general with contempt is I think counterproductive.