One of those gospels is how you should never break the back button in a web browser. I was just looking at a fancy flash slideshow on flickr with Meena, and as the last picture scrolled by she asked me which picture I liked best. She grabbed the mouse, hit the back button, and suddenly we were back on some other pictures page. "What the hell?" she asked. "Where did it go?"
It's too easy to forget that the real users, the real majority of people, who use these silly programs we make are people like her.
(Now she's reading Wikipedia: "Who writes this stuff, Evan?"