There are many good websites that talk about color, color theory, color theorists, and just about any other aspect of color you can imagine. Here are a few that are useful.
Color Matters - Color Matters is a general website about colors and has some interesting resources that will be helpful.
Exploratorium - The same museum that makes the Color Uncovered app has some great information on their website.
Handprint - Handprint is primarily a web site for watercolorists, but they have a great deal of information about color and color theory.
RIT's Program of Color Science / Munsell Color Science Laboratory - The Program of Color Science at Rochester Institute of Technology is one of the world's foremost color science research and educational organizations. This website provides high quality information that you should definitely look at if you're researching color.
Colour chart / Green / from: Chevreul E: Colour chart / Green / from: Chevreul Physics/ Chromatics (source: Image Quest)