• Complete blindness. Create a logical document flow to support screen readers
• Low vision and color blindness. Optimize images and color schemes, and ensure your site enlarges gracefully
• Hearing impairment. Provide video captions and visual alerts for interactive features
• Physical disabilities. Make forms, popups, and navigation easier to use
• Cognitive disorders. Adapt fonts and text styles for dyslexic users, and design consistent, well-organized pages for people with ADHD

http://www.amazon.com/Accessibility-Handbook-Katie-Cunningham/dp/1449322859