Links to some resources on Web Accessibility:

• WAI: Web Accessibility Initiative: http://www.w3.org/WAI/
  
• Web Accessibility on Wikipedia
  
• What Is Web Accessibility? by Trenton Moss
  This article will tell you who you need to consider when making your website and what their unique requirements are.
  
• Dive to Accessibility by Mark Pilgrim
  This book answers two questions. The first question is "Why should I make my web site more accessible?" If you do not have a web site, this book is not for you. The second question is "How can I make my web site more accessible?" If you are not convinced by the first answer, you will not be interested in the second.
  
• Building Accessible Websites by Joe Clark
  Contains: A declaration of what accessibility is and should be, Why make Websites accessible?, How do disabled people use computers?, What is media access?, Problems with images, texts, and links, etc.