My position is that this should be a matter of individual choice and I am entirely against compulsion. In my view there are arguments both for and against helmets for cyclists. There is a reasonable case to be made out for helmets but it has been greatly overstated by enthusiastic advocates. For a good well-balanced discussion of the issues with useful links see cyclehelmets.org. The British Medical Association has a sensible article on the subject (Carnall D. Cycle helmets should not be compulsory. BMJ 1999;318:1505). Unfortunately, however, the BMA has now changed its position on helmet legislation.
For an excellent critique of the BMA position, see this article.
Do I wear a helmet? Since I think it's something you should make up your mind about for yourself, I'm not saying (though my pictures may give you a clue). I'd only advise you to keep Dr Samuel Johnson's advice in mind: "Clear your mind of cant, Sir!"