There is a solid way to validate sites against the emerging accessibility guidelines on the web. The
Cynthia Says validation application can make sure your code is up to par using a wide variety of emulators.
I have been very interested as of late in the emerging world of Web Standards and Accessibility. It is a good practice to follow, especially if you are developing for a wide audience with regard to age and usage experience. Many of my sites do not have the most savy users and therefore and accessible site is a great asset.
You can learn more at:
W3C
Web Standards Project
Cynthia Says Portal