I don't wear a helmet. I do have one, and have worn it a few times and when out mountain biking. I do wear a helmet when mountain biking as I like to go nuts. Other than that, even though I've had a few spills, I still don't feel a need for a helmet. Here in Colorado, more cyclists wear helmets than motorcyclists. Bicycle helmets were never a big thing until people started watching Greg Lemond win TDF's. In checking out how effective a typical cycling helmet is, I found that it can save you from concussions, but that hunk of styrofoam won't save your life. I've heard the stories of people who believe the helmet saved their life after crashing through a windshield. The thing is, there are people who crash through windshields without helmets and survive anyway. Go figure.
With all this said though, I'll probably get that new Azonic helmet that has speakers for IPods. As its' probably the best way to listen to tunes without sticking foreign objects into my ear.