AZ
In AZ, if you are below a certain age, you must wear one. Otherwise, eye protection is the only requirement of the law. (Protect the eye, but not the jello which controls the functions of the eye????)
I personally believe if there are seat belt laws, there should be helmet laws. I believe a (state or fed) government's primary purpose is to serve its people. Secondary is to protect its people...even if it's from themselves. Ironically, m'cycle cops are required to wear helmets on duty, why is that?
Besides, if anything could give you the slightest chance of surviving an accident, why would you not want it, if one claims to love this activity so much???? Live to ride another day, and like it was stated above, the gear is a freakin' awesome compliment to the bike.
I rarely ride to work, but when I do, many stop to make comments about riding ("donor-cycle", "I know so-and-so who died", etc), but they all were initially attracted by the gear hanging up. I could still see the excitement in their eyes, and how they secretly wished they had the courage to do it too. Some even try on the helmet, while lecturing me on how dangerous m'cycling is, but they all say "At least you wear the gear", as they feel the texture of my jacket and "ooh-ah" at my m'cycle calendar.
After every single ride I look at the minute chips in the face shield from the many insects that exploded on it, and I also notice the chips from bouncing rocks that hit the helmet and just thank myself for wearing more than a napkin on my face and some sunglasses.