ergophobe - 3:21 pm on Sep 15, 2010 (gmt 0)

Well, as a starting point, if you haven't already, you'll probably want to peruse the Web Accessibility Iniative pages at W3C.
[w3.org...]

That's sort of a portal for such thing. In particular, look at the Web Content Accessibility Guidelines
[w3.org...]
which include some handy checklists and guides on how to become compliant.

That will also lead you to all sorts of tools that you can use
[w3.org...]
The classic one is Bobby (commercial) and WAVE is a nice online tool (free).

There are a variety of specific tools, like contrast analyzers (like this one [visionaustralia.org.au]) and so forth for specific tasks.

And of course, there's the FF Web Developer toolbar - surf with Javascript disabled - and trying to surf your site without a mouse (logical tabbing for forms and so forth).