Public service announcement: some 8% of men have some form of colorblindness.
A couple of people have pointed me to this nice article on colorblind-friendly design, by Masataka Okabe and Kei Ito. Useful reading for anyone who designs for print, presentations, or UIs.
It's a good overview of the underlying theory/physiology of colorblindness and gives many tips for conveying information through channels other than color.
The authors also provide this handy colorblind-friendly color palette: