Colorblind people are only just one small group that need to be considered. Since not many sites use a blatantly impossible color scheme (truth be told the last

Colorblind people are only just one small group that need to be considered. Since not many sites use a blatantly impossible color scheme (truth be told the last time I've been told by a colorblind friend that there was a problem was back when Apple used red and green dots for iPhone availability (2g, not 3g), now Apple's using shapes and colors), I'd say the bigger accessibility travesty I can think of now are sites that use image-based captchas with no alternatives (audio, answer a question, etc.). Grrrr. Not to say I don't think much of colorblindness (I still test for that on the sites I work on, there are some excellent tools around for that purpose), and not to say that I love spam, but I hate those particular types of captchas.