One of the best CSS coding tips I've read in a long time actually has nothing to do with CSS. Jan Holzmann of Snippit.net wrote an excellent article about using the meta-refresh property to save time reloading browsers when you have to test your CSS in several browsers.
It's as simple as it sounds. Just add the following two lines in the head of your document, and then your browser window will automatically refresh as you make your changes.
<meta http-equiv="refresh" content="10; url=http://localhost/index.html" />
<meta http-equiv="pragma" content="no-cache" />
This should be really handy working in a dual-monitor environment like mine.