Color Blender
"This script blends three user defined colors together and mixes the result with the requested amount of black and white. It was written to allow the mixing colors from a triad to determine what colors are possible for a given triad.
Recent update: This latest version uses a different - hopefully more natural method for mixing the colors. Now you mix the colors together in a manner reminiscent of mixing 'real paints.' You mix them by parts."