Excellent CSS presentation from stopdesign
Highly informative, useful and beautifully designed Pushing Your Limits presentation by Doug Bowman for the Sydney 2004 Web Essentials conference.
Basically, tells you why and how you should design with CSS, Cascading Style Sheets. If you don't know, Cascading Style Sheets, while it won't save you and is not a solution for every interface problem you have, is this simple, almost boring technology which allows you to separate the presentation of your site from the actual data in it. Fantastic for design and allows almost effortless changing of site design.
For instance, the hour change it took to change the layout design of this blog was possible because of CSS. Basically, all controlled by one file telling the browser how to lay things out. If you're not using css currently, you should get up to speed.
If you do any web work or are interested in this stuff it's a simple, very informative design read. Some really nice design and branding advice too using the Blogger and Wired redesigns as examples.