Fluid wiki - accessibility for markup
http://wiki.fluidproject.org/display/fluid/DHTML+Developer+Checklist
Accessibility plugin for JQuery (tabindex and others)
https://source.fluidproject.org/svn/sandbox/tabindex/trunk/examples/
Also examples showing accessible samples of each kind of HTML control
Links to Mozilla documentation
http://developer.mozilla.org/en/docs/Key-navigable_custom_DHTML_widgets
http://developer.mozilla.org/en/docs/Accessible_DHTML
Recent blog by YUI on nature of new ARIA roles:
http://yuiblog.com/blog/2007/12/21/menu-waiaria/
Upcoming workshop, syllabus is useful: