PageScreamer

PageScreamer dramatically reduces the time required to correct Web content
for compliance with the standards of Section 508 of the Rehabilitation Act.
Includes Verification and Correction in a single easy-to-use product.
PageScreamer is a Java-based, multi-platform product that supports multiple
file types and provides advanced support for nested tables and universal
corrections.  

http://www.crunchy.com/tools/index.html
http://www.crunchy.com/tools/PageScreamer.html