Accessify.com lists a collection of useful Accessibility tools to help you both develop and view any site with accessibility in mind.
The tools include everything from Favlets, add-ons for Dreamweaver to a recent alpha release of Accessibility Toolbox 1.0
www.accessify.com/tools-and-wizards/default.asp
The site also contains a useful favlet tool which lets you label and show div id’s of a page without viewing the source code.
www.accessify.com/tools-and-wizards/accessibility-checking-favelets.asp