Accessibility in Distance Education (ADE) website

If you haven’t come across this website yet, it’s a great place to start, Accessibility in Distance Education from the University of Maryland University College.
From their homepage:

The Accessibility in Distance Education (ADE) Web site focuses on helping faculty develop accessible online learning materials for people with disabilities. It is divided into five major sections, targeting common accessibility questions.

The five major categories that they mention are What is Accessibility, Legal Issues, Understanding Disabilities, How-To and Best Practices.
While there are many great resources specific to distance education here, much of the site addresses accessibility issues in general.