some more unlisted tools (resent)

others (resent)
yellow pipe lynx viewer: http://www.yellowpipe.com/yis/tools/
infoaxia japanese lynx simulator: http://www.infoaxia.com/apps/pub/lynxsimulator/
Q42 colour blindness simulator: http://www.q42.nl/demos/colorblindnesssimulator/
Infoaxia web accessibility toolbox: http://www.infoaxia.com/tools/iawat/index.html

Juicy studio: 
image analyser - http://juicystudio.com/services/image.php
complex tabel inspector - http://juicystudio.com/article/firefox-table-inspector.php
colour contrsat analyser - http://juicystudio.com/services/colourcontrast.php
readability test - http://juicystudio.com/services/readability.php

drempelvrij.nl toolbar (dutch) - http://www.drempelvrij.nl/toolbar/index.html
web developer toolbar: http://chrispederick.com/work/webdeveloper/
checky: http://checky.sourceforge.net/extension.html

regards
steve