ColorThink

I was introduced to this software by Mac Holbert and Ming Tsching of Nash Editions.
CHROMiX ColorThink™ is a color management toolset that helps you understand color better than ever before. The toolset has nine modules for visualizing, evaluating & solving color problems. You can overlay the color space of your image file with the color space of your printer/paper combination to see how they compare. Very cool. Link