Building sites to make them accessible to as many users as possible need not be a biblical ball ache. Going through a few simple checks you can quickly get an idea how your page will look to a person with a disability.
One of the easiest things to do is use correct ALT tags especially for inline images and spacers. The RNIB (http://www.rnib.org.uk) suggest the use of alt="". This could be done site-wide by a find and replace or by using the accessibility extension for dreamweaver (yes I know ;))
Obviously it is much easier to design an accessible site from scratch than to do it retrospectively but that does not stop you trying. I would suggest that if you are trying to improve accessibility you will not be the first in line to have a law suit against you, that will reserved for the real bad boys or the people who should know better. [news.bbc.co.uk...] (halfway down)
In the UK sites will need to be Priority 1 WAI compliant due to SENDA and as part of a possible EU directive may even need to be Priority 2.
Other Things to Consider and test for:
Work towards validation of HTML and CSS
Bobby, not the easiest to follow but will give you a good idea where to start
Turn all images off and see if you can navigate the page (related to alt tags)
Turn off style sheets and see how the content looks, does it still make sense (if you are unable to turn them off temporarily move the CSS file)
Use the largest custom font size (always use relative font sizes)
Resize the browser window (see if you have to scroll across the page)
Navigate using only the keyboard (some people cannot use a mouse)
Press tab to move through links (as above)
Check link text for information on where it will lead
Disable scripts, applets, animations (flash etc, a lot of people surf with Java disabled)
View page in black and white
Set colour monitor to high or low contrast
Test for colour blindness problems [vischeck.com...]
Pass the page though a text only viewer, if you cant make head not tail of it, you may have problems [delorie.com...]
Just a few things to consider and perhaps act upon, especially in the current litigative world we live in. After all it would be really bad PR (thatís public relations not PageRank :)) to be the first to be branded as discriminatory towards the disabled.
Just my musings.