I wasnt going to post on this because there are two distinct groups of folk on this board, I have read posts where members say, "I WILL go through a red light / stop street - and then try and justify it by saying "when its safe" and others who are obviously in the "obey the law" camp. Personally, I have seldom had an issue with motorists, perhaps its an "attitude" thing, but like Ianj said, I too raise a hand to thank motorists at intersections, if a truck is coming up behind me, I try and ride as close as safely possible to the edge of the road, I raise my hand and acknowledge I know he is there, at lights and stop streets I try and make eye contact with motorists when I feel I dont know where they are going, we are all humans, they understand just by my look or appearance I am in question and they either wave me on or take action which I can anticipate, I make myself visible with bright lighting, even in the midday, its just a habit and if it makes one motorist happier because I was more visible, I consider it a good thing. However, and I am not been critical, many cyclists have the attitude of, :I deserve to / have a right to be here" or "I have right of way so you better wait" or constantly ride around with a "#$%^& you" look on their face. Believe it or not, I firmly believe you WILL be treated as you treat others. There may be a few odd exceptions, but I dont concern myself with them, I concentrate on smiling, thanking, and generally putting out good vibes towards motorists - and as I say, for me it works and I am usually well accepted as part of the moving traffic. Try it, what have you got to loose.
