designing a usable website does not mean that you have to leave out all the fun stuff, like Flash, DHTML or similar. The (careful) use of new technologies can indeed make your site more usable, eg. when using Flash to replace raster graphics, when appropriate (of course, you'd still want to provide the image in a way accessible to all). As with all design skills, you should know the rules and then carefully break them.

A usable site IMHO adresses the following issues: