I tried to stir up a helmet kerfuffle a few posts ago, but to no avail. How do you know your blog is unpopular? When you can't even get a decent pro-/anti-helmet flame war going in your comments. But, undaunted, I will try yet again.
Usually, I take a pretty laid-back, semi-agnostic approach to what one wears upon one's melon while riding. I wear a helmet when I ride, and I ask that anyone on the back of my tandem do the same. Beyond that, what you do on your bike is like what you do in your bedroom: sweaty, marked by a lot of grunting, and none of my dang business.
My agnosticism collapses into pure zealotry on one point, however. If you ride around with your helmet hanging from your handlebars, I will harangue you relentlessly until I am out of earshot (which won't take long, because I'll be trying to ride away from you at my laughable excuse for top speed). Why? Because while I can see some validity to both the pro-helmet-on-head argument and the leave-helmet-at-home argument, there is absolutely NO rational reason for riding with a helmet hanging on your bars. You're still carrying the weight of the thing (albeit not on you), so it's no lighter. And what happens when (not if) the helmet falls off your bars into your front wheel? You're going down, and you're probably taking out several people around you... and the thing that would protect you in a crash is the thing that sent you over the bars in the first place. Irony, thy name is concussion caused by protective headgear.
So, do yourself and everyone riding with you a favor: Either wear the thing or don't. But don't use your bike as a rolling hat rack.