I came across this great list of usability rules in a presentation by Denise Stephen called “Enabled by Design meets Scripting Enabled” which was given as part of the Scripting Enabled event organized by Christian Heilmann. Here goes the list:

Usability - The golden rules

<li>Simply presented information</li>
<li>Content reduced to essentials</li>
<li>Manageable logical structure</li>
<li>Intuitive usability</li>
<li>Uniform appearance, consistently designed</li>
<li>Good design and appealing graphics</li>
<li>Quick delivery of information</li>

There are some great slides at ScriptingEnabled which are up on Slideshare - like this one Why I hate the Interweb (a presentation on the challenges that face different kinds of disabled users online). View more on Scripting Enabled website.