Doing a lot of research for my new job regarding accessibility standards for disabled users of the web, and have a couple of good resources for anyone doing any kind of web design these days.
Online Accessibility Course from the University of Florida
Very good tutorial, with a ton of information that I would have never thought of on my own, like putting in links to skip navigation bars so that visually impared users can skip them in order to get to the content with a screen reader.
The NIDE Cascading Style Sheet Generator from the University of Toronto
A style sheet creator specifically designed for local CSS use for various disabilities. Allows you to create CSS for visually impared, motor-skill difficulties, and other differently abled patrons.