@Helmets
I live in the Netherlands, and as people know: lots of people riding bikes here and almost no one wears a helmet. As it is, most accidents involving cyclists are usually side impact from a car, and the helmet would not have helped. On the other hand, here we have a lot cycling paths (either free-laying or a reserved strip on the main road), which probably makes it a whole lot safer then in countries without a developed cycling-culture.
When I was in school I had to ride 30 km by bike daily (15km to school, and 15km back) and had some 'accidents' (linking of handlebars with the friend next to you, slippery roads, racing cyclists who don't yield). In my experience, you usually are able to break your fall and as a result are more likely to hurt your hands, arms or knees (or maybe your balls) then your head.
In my opinion the benefits of a bicycle helmet is grossly overrated (as almost all other Dutch seem to think), I only think they can have some benefit for:
1) kids: inexperience and small posture will make it easier for them to hit their head, and the helmet will probably not save more lives, but prevent them from crying (negative effect in the Netherlands: more likely to be bullied by other kids without helmets)
2) racing cyclists: racing in a large group of cyclists makes it more likely that you cannot anticipate and break your fall, or that someone in behind you drives over you