Web Design Smells

Suggestions of web interface or technology techniques to avoid:

Using "high-end" media where something simpler will do. For example, using JavaScript when plain HTML would do the job nearly as well, or flash animation when an animated GIF could do the just about the same thing.
Avoid media vendor dependency. Provide sound and video in at least two diverse formats. Getting media files to play can be a pain as different or bad codecs can make them unplayable. Include at least two diverse format choices for active media. For example, include both a QuickTime and a MPEG version of a movie.
- Actually, the better answer now seems to be to use Flash, since that has a better chance of being viewable on any given computer than either QuickTime or MPEG. I have yet to use any machine that had trouble using the Flash-based player on YouTube, for instance.
- WhatsWrongWithFlash
Assume the user is using massive screen resolution such that the page is nearly unusable on smaller-resolution monitors.
- Related: Don't disable scrollbars