Found this great site about Amsterdam Bicycles Lots of pics too.
I am back and forth with the helmet thing so you make your own mind up.
3. No Helmets EVER - It is amazing to me coming from San Francisco, land of 100 percent helmet covered heads, but in all of Amsterdam (population 750,000) there is not one bicycle helmet found anywhere in the city. Not ONE!! Contrast this with San Francisco, for anybody under the age of 18, there is a Mandatory Helmet Law, and everybody above 18 wears helmets anyway. Now faced with this shocking disparity, I think any reasonable person must come to the conclusion that either the people in Netherlands do not value the safety of their children, or San Francisco bicyclists are clumsy pansies with soft heads and weak minds that must be protected from hurting themselves no matter how much it infringes on individual rights. more here