Found another great information resource for SharePoint branding with this blog from Michelle Pakron. In her blog, Michelle goes to what certainly appears like great lengths to visually breakdown the various CSS elements/styles of an actual SharePoint page. If you're s SharePoint designer, then of course you already have come to rely on Heather Solomon's CSS Guide for WSSv3, but I also really like Michelle's contextual break-down. It's worth your time to check it out. Here's an example of what I'm talking about: