6. Love thy Surfers and Visitors
Design for "last year's" technology so surfers using 56K modems can download and use the site quickly and easily. If you design only for people with high-speed Internet connections (DSL and cable) you have eliminated 85%+ of your potential market.
7. Thou shalt not Annoy
Use only stationary text and graphical layout elements. No Scrolling text, marquees, or animations of any kind, including rollover buttons.
This "eye candy" steals valuable bandwidth and adds little to a site's main purpose, especially for returning visitors who just want information, not a carnival sideshow.
8. Thou shalt Not Scroll Left or Right
Design your pages so they never force a visitor to scroll left or right, no matter what the resolution settings on their monitor. Sites that read "best viewed at 800 x 600" really say "look at it my way because I don't care about your preferences or limitations."