accessibility checkers
Accessible Data Tables
Accessibility Valet Demonstrator
Bobby Online Service
Colour Blindness Simulator, Colour Contrast Check, Online Accessibility Check
Evaluating Web Sites for Accessibility with the Firefox Web Developer Toolbar
GrayBit v0.5: Grayscale Renditions of your pages
UI Site check
TAW: Web Accessibility Test
Total Validator
Truwex accessibility Validation Tool
WAVE 3.5 Accessibility Tool
Web-based Site Usability Checker
WebXACT Quality & Accessibility Check