Estimates are that around 8% of the male population has some form of colour blindness, this can cause problems for sufferers when surfing the internet especially if websites are designed without taking this into account. http://wearecolorblind.com/ is a website loaded to bursting point with resources for web designers and developers. Well worth a visit.
There is also a load of resources at http://www.colblindor.com/ including a fascinating Colour Blindness Simulator.
