>>You're right, I studied this problem, and how to handle it: the result is, if you're going to use colors to differentiate, you should let the users select their own colors for the text or background. Then even color-blind individuals can choose colors which are good for them...
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>Well, what if they can only see black and white? Then a great UI idea will be useless for them.
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>I think I'd use something else, like underlining, boxing, an asterisk, etc. It wouldn't look as cool, but it would be immediately useful to all users.

According to my study (I read some studies & articles), no one is so bad as to see only black & white (what a weird world that'd be :). Most color-blinders have either only red-green or blue-yellow trouble. But no matter how unable to distinguish colors they are, they become very adept at distinguishing shades of gray, it's a kind of survival skill.

Therefore, allowing a good variety of color choices will enable them to choose a scheme in which they'll be able to differentiate reasonably well...after all, it was noted, they have the same trouble elsewhere in life (how about traffic lights, e.g.), and they deal with that successfully...