We are Colorblind » Patterns for the Color Blind
A pattern library that considers colour blindness.
Color Oracle
A very handy little app that sits in your menu bar on OS X and can instantly show you how your screen would look if you were colour blind.
Related links
Designing for colorblindness - The Verge
In design, both in the digital and physical worlds, color should never be the sole indicator of meaning. A simple test: if your work was converted to grayscale, would it still be usable?
Andy describes life online with deuteranopia and dispenses some practical advice for designers:
If there’s any uncertainty, adding labels, icons, or textures to each meaningful color of your design will make it accessible to many more people, regardless of their ability to perceive color.