Color Changes in Mac OS X for the Visually Impaired?
During WWDC this year, one of the presenters showed how certain files can have ICC profiles embedded in them that can translate the color palette in radical ways. They were using this to verify that apps were using colorsync correctly and not double applying it. After this, I started digging and (in Panther, anyway) you can use ColorSync Utility to install custom output filters to adapt colors any way you like.
For instance: They include an output filter for CMYK (4-color printing) that prints everything in sepiatone.
There's absolutely no reason at all that this facility couldn't be used to do some funky color translations for the screen to help color blind people see it better. Obviously, this would require a better knowledge of the various types and degrees of color blindness than I have, but it could be useful to many and should automatically effect all apps on the machine