Please, without getting into the whole helmet debate and their efficacy...
I was up in NYC this weekend and was amazed that in the hundreds of ppl on bikes I saw over the weekend, I only saw three wearing helmets. Whatever side of that fence one sits on, generally it seems that helmet use and acceptance is fairly widespread and that their efficacy (true or not) is well accepted. It struck me odd that in a city where there are so many cars, cabs etc weaving in and out that most bike riders would feel it illogical to wear one.
...and along that line, blinkies were almost as rare as helmets. Certainly nothing like many of the commuter setups around here.
Are NYers just tougher than the rest of us, or is life there so miserable bike riders don't care what happens?