Easy Page Layout Grids from Yahoo!
I found out that Yahoo! has a whole developer section with lots of great information for developers. One of my favorites is the Yahoo! UI Library: Grids CSS It allows you to use CSS to layout your page and if you ever want to change something it can be as easy as changing one character in the markup to have a new layout. You can move the sidebar from the left to the right or change the width of it, or completely remove it, for example. There's also a way to stack special grids in the main content section to allow for just about any design you could want... Check it out.