Web Developers and Designers: This book teaches them how to use their chosen technologies to create and validate accessible content, including XHTML, CSS, JavaScript, PDFs, and Flash. That covers a very large potential audience.
Business managers: This book teaches them what impact web accessibility will have on their businesses; also a large potential audience.
Web accessibility not just morally sound - there are legal obligations as well
Very large potential audience, consisting of web developers and business managers
Very little competition to this book