Ok, I was going to cut and paste a few of the more important point/counter points but because I am lazy I will just give you my take-

Firstly, any study that shows a helmet reduces injuries is fine. I am not going to argue that wearing one does you no good when your head hits something... But I will tell you this, at one time I was a top tier athelete, and I am not talking about riding. I was a 4 year varsity gymnast in high school, then I went on to (now don't choke on your breakfast) play basketball in college. I can take a fall with the best of them, but I am getting older. (late 30's) Now why tell you all of this? Well, when you train as a gymnast, you do it in two ways. One, with a spotter or a rope harness system connected to you, or two, free and with no spotter. Guess where the danger is? Guess when one takes the real risks and pushes the envelope? Can you guess where I am heading here yet? Yes, it is the same with a helmet for me. If I have my helmet on it is usually because I am racing in a time trial and I will be hitting 55mph at some point. Or, maybe I will be riding with a pack, or down an insane fire trail... Do I wear my helmet in these circumstances? Yes, even with my still somewhat cat-like reflexes, I do indeed wear the helmet...

Here is where it gets tricky- Do I wear my helmet when I ride around the block? When I ride on a bike trail? When I go to get groceries? When I do something mundane? Never. Why? Well, baring some joker trying to kill me in a car, and yes this could happen, I know that I am going to be just f'n fine. My life, my choice.

Ban tobacco, alcohol, and McDonalds first please. They take WAAAaaaaAAAAaaaAaAaAAAAY more lives than those of us who chose to not wear helmets. Get that all done first THEN you are more than welcome to give me crap about me not wearing my helmet when I chose not to.