I'm reading Steve Krug's book Don't Make Me Think! A Common Sense Approach to Web Usability and there are a few good sources that he points to that will help designers design more accessible interfaces. Here are some of the ones from the book.
- Guidelines for Accessible and Usable Web Sites: Observing Users Who Work With Screen Readers (PDF) - Published in the ACM Magazine, Interactions (November-December 2003). With permission from ACM, Janice Redish has made it available for personal use, so please do not redistribute.
- Web Accessibility Checker, by Total Validator
- Building Accessible Websites by Joe Clark
- Constructing Accessible Websites by Jim Thatcher et al.
- Maximum Accessibility: Making Your Web Site More Usable for Everyone by John Slatin and Sharron Rush
What else is out there? For software? For physical interfaces?