Design for Colour blind people

Advert test
I know that most designers hate limits on design - and I respect that - but the web can be really difficult if you're colour blind (e.g. click on the green button - well, I don't really see green)

This is a great site - I'm surprised (if) I haven't shared it before

Vischeck: Examples

I have protonopia apparently.

Given that 1 in 7 men suffer from this in varying degrees (my cousin's son recently was refused entry on a mechanics apprenticeship due to a colour blind test) - would designers consider this and take it into account?
Thanks Byron. Technically, every site should use, disability sector not!

Accessibility law - providing a website that someone can't use due to a disability is essentially discrimination. Ok, tough law but good to think about