Web Accessibility initiative
This web site develops: 1) guidelines widely regarded as the international standard for Web accessibility, 2) support materials to help understand and implement Web accessibility, and 3) resources to make web sites accessible to people with disabilities.
This site mainly includes Introducing Accessibility, Guidelines & Techniques, Managing Accessibility, and Evaluating Accessibility sections. As a designer, what is more interesting to me is the ten tips for making accessible web sites. These ten tips have taught me quick and easy ways on how to design images, hypertext links, graphs, and so on.