|Color Brewer 2.0||
Web-based tool for selecting appropriate color schemes based on your data type: qualitative (also called categorical), sequential, and diverging. Includes options for color-blind safe schemes.
|Coblis||A color blindness simulator|
|Colblindor||Site for learning more about color-blindness. Includes tests and tools for checking designs (Coblis)|
|Perceptual Edge||Stephen Few’s website on tools and techniques for visual business intelligence.|
Stephen Few's Practical Rules for Using Color in Charts is an excellent summary of how to use color effectively and how to avoid common mistakes with color display.
A. Light & P.J Bartlein's The end of the rainbow? Color schemes for improved data graphics. Eos, Transactions American Geophysical Union. 85:40 (2004): 385-391.