Microsoft's Accessibility Website

This section of the Microsoft website provides a wide range of resources for developers and end-users.

http://www.microsoft.com/enable/



W3C Guidelines for Disabled Accessibility

The guidelines issued by the W3C (see the Web Standards page) are
generally considered to be the definitive reference work on this
subject.

http://www.w3c.org/wai/



WebABLE

WebABLE is the authoritative website for disability-related internet
resources including white papers, news, guidelines, standards, tools
and utilities.

http://www.webable.com/

Employers' Forum on Disability
The Employers' Forum on Disability is the employers' organisation focused on the issue of disability in the workplace. Their publication Accessible Website Design provides a good deal of practical and strategic guidance.
http://www.employers-forum.co.uk/

Jakob Nielsen's Usability Website
Jakob Nielsen is one of the most prolific writers on the subject of website usability and disabled accessibility. His opinions do not meet with universal agreement, but they are frequently the stimulus for a vigorous debate.
http://www.useit.com/