I was reading Christian Cantrell‘s weblog and i found a very useful link which display in the left sidebar of your firefox browser the javascript reference (css, dom, xsl, html, unicode tools).
In order to use check it out by saving this URL as a bookmark, and checking the ‘view in sidebar’ option in it’s properties: http://lachy.id.au/dev/mozilla/sidebar/sidebar.xul
Also very very useful the unicode tools

http://lachy.id.au/dev/mozilla/sidebar/sidebar.xul