Accessify.com
Tools, wizards, articles and tutorials on Web Accessibility for the conscientious web developer.

A-Prompt Repair Tool
A-Prompt (Accessibility Prompt) is a software tool designed to help Web authors improve the usability of Web pages created in HTML format. It first evaluates an HTML Web page to identify barriers to accessibility by people with disabilities, then it provides the Web author with a fast and easy way to make the necessary repairs.

Bobby
Watchfire WebXACT is a free online service that lets you test single pages of web content for quality, accessibility, and privacy issues.

Cynthia Says
The HiSoftware Cynthia Says is a web content accessibility validation solution, it is designed to identify errors in your content related to Section 508 standards and/or the WCAG guidelines. This online test only validates one page at a time.

Magpie (multimedia)
An authoring tool for making media materials accessible to persons with disabilities, the Media Access Generator (MAGpie) is used for creating captions and audio descriptions for rich media.

Wave
WAVE 3.0 Web Accessibility Tool

Vischeck
Vischeck is a computer simulation of the entire process of human vision that simulates colorblind vision.