It's amazing how one question can make you thankful for something you have, or in this case, don't have.
I was asked at work today essentially what could be done for a document to make it more color blind friendly, as it was using red to make text stand out. This got me to wondering, as it is something I never really thought about before, yet it affects more people than we realize.
"How to make figures and presentations that are friendly to color blind people" takes a look at giving scientific presentations that are friendly to color blind people. It goes into the 3 types of color blindness and also reports that "(o)ne in twelve Caucasian (8%), one in 20 Asian (5%), and one in 25 African (4%) males are so-called "red-green" colorblind. It is commoner than AB blood group."
Searching for information on color blindness and web usability eventually led me to Vischeck, which allows you to see how an image or a page of a website looks to people for each of the color blind types. Check it out, it's definitely an eye opener. It definitely makes me thankful that I am not color blind.