We Are Color Blind [wearecolorblind.com] is an online repository consisting of design patterns and constructive critiques of existing examples for anyone who designs, develops or is in another way involved with creating content for the web.
Interestingly, most of the available content deals with data visualization, ranging from simple design patterns (e.g. Line Graphs, Pie Charts and Status Icons) to the analysis of the color readability of existing visualization examples (e.g. Ben Fry's Visualizing the Major Health Issues, the streamlines used in the Wakoopa reports, or the World Map of Social Networks).
Any visualization designer should feel highly encouraged to at least be aware of the Quick Tips list.
Via Swiss Miss.