Tinderbox CSS Tutorial
Scott Price begins a promising tutorial series, in which he walks step-by-step through a CSS re-implementation of Derek Powazek's Simplicity Templates.
First, by making your html use CSS you're separating the content from the presentation. The html that results is *much* easier to read because it pulls the html junk out of your beautiful entry. Secondly, if you are using CSS to change the layout, you can do crazy things like CSS Zen Garden does. If I have my way, the end of this process will be one set of templates, three stylesheets, and three completely different looks.