We Covered The Basics
We have covered the basics from using alt and title tags all the way down to making sure your site works with tabed browsing. It is important to keep in mind that some people have problems or maybe just do not like doing things one way and that giving them another way of doing it will make them happy and keep them on your site.
A lot of the changes we made like adding in alt attributes and title attributes will actually help your site with search engines as well because spiders are able to read that data so when doing these changes realize you get at least 2 things out of them. You get users that are better able to navigate your site and use your site better and you get search engine spiders that can now navigate and understand your site better. There are not many changes you can make to a web site that give you two very desirable effects so when you find the ones that do it is important that you implement then.
A lot more information can be found at http://www.w3.org/WAI/ as well as http://www-3.ibm.com/able/guidelines/web/accessweb.html. There are a lot more tools out there that can help as well and we will be writing more articles on the subject so check back often.