Good timing. I'm currently working on an existing app that is targeted specifically at those with accessibility issues as part of a larger service offering. More so towards those with hearing issues.

This is a good first step, I have been using the WAVE accessibility plug in for Firefox to identify missed issues in my first run through of the app.

Luckily, we have an employee with a visual impairment that we can utilize for real world testing of the app.

This really is its own specialty.