Color:

What is color?

The Physiology of Human Vision
color.pdf

Color and Culture
http://www.colormatters.com/brain.html

Basic Digital Color Information:
http://www.arts.rpi.edu/%7Eruiz/IMAGING/color.html

Color Theory:
http://www.worqx.com/color/index.htm

Color Theory for Digital Displays
Part I
Part II
Applying Color Theory for Digital Displays

Basic Color Theory:
http://www.colormatters.com/colortheory.html