Hi i did a huge posting on this for cavalier lady's site a while back. pasting in the relevant bits here:
/begin pasted/What I *am* suggesting is that as you already give a good and ethically run/based service that you have a think about ways of letting people with special needs know about it.
If you're interested and have any spare time (interesting concept that - hmm - "spare time" I wonder what it means.) Here's a few links to get started
for a good overview and a wonderful set of links start here:
http://html.about.com/compute/html/cs/accessibility/index.htm
(By the way the about guide for this topic pleads with people to let her know when you do such pages and recommends such sites to visitors.)
Microsoft have some fabulous stuff too, start with these:
http://www.microsoft.com/enable/dev/web/checklist.htm
http://www.microsoft.com/enable/dev/web/HTML.htm
http://www.microsoft.com/enable/dev/web/resources.htm
and here's the link to their resources page :-)
http://www.microsoft.com/enable/dev/web/resources.htm
Not to be out-done IBM have also some great stuff - I love their checklist:
http://www-3.ibm.com/able/accessweb.html
Kind regards,
Mark
/end pasted/
Hope this is useful to you