Other
Worqx: Color Systems
In an continuing overview of color and color theory, this site focuses on color systems from Subtractive Color (CMYK color system) to Additive Color (RGB colors).
Other
Golden Artist Colors: Color Mixing Guide
Golden Artist Colors presents a guide to mixing acrylic paint. An explanation of color theory and mixing color with paint is included on this site. There are also color charts and exercises that can be done with paint that explore how...
Wikimedia
Wikipedia: Graph Theory
Wikipedia provides an introduction and overview of graph theory. In addition to introducing the basic terms, there are related links to classic problems in graph theory such as the traveling salesman problem and Dijkstra's algorithm.