Sites which look awful in very new or very old browsers.

Before selecting a website vendor ask them about website compatibility. Do not let them tell you that "only" 10% of users have that type of browser, or only 15% of users have that operating system. The reality is only a fraction of website users will have the latest operating system, the latest browser and the highest screen resolution. Ignore the minorities at your peril! There is no reason why you can have a fantastic and effective website presence that is viewable and usable by well over 95% of Internet users. Ensure that your website looks great and functions correctly:

• On both PCs and Macs.
• Using FireFox, Explorer (versions 5 and up) and Safari.
• On monitors starting at a resolution of 1024 x 768. While there are still 800 x 600 resolution monitors out there, building a site for that size screen will limit the effectiveness of your site for the vast majority of users.
• When measuring up to W3C compliance.