The power of Office Live Small Business's advanced design features lies in the access they provide to the underlying data. Most people use the Custom header, Custom Footer and Custom Navigation modules to simply add static html. While that may serve the purpose, it involves a lot of work because you have to maintain all the links in your header, footer, and navigation manually. And God forbid, if you decide to change the site design, you'll have a major project on your hands.
By making use of the XSL style sheets that these modules offer, you can use the links and navigation you've set up in Office Live's site designer. Here's an example: I wanted to make a small web site for my company. I wanted it to look like Acxede.Net, but I didn't want to write all the code. So I created a template using the Custom Naviagation and Custom Footer modules. (I didn't need the Custom Header module because my header and navigation are lumped together in the Custom Navigation module). Then I adapted Acxede.Net's stylesheet and applied to my Office Live site. That's it. I didn't have to code the links manually. The modules picked up the navigation and footer settings from the Site Designer. Here's the result
www.acxede.com: go there.
As you can see, it looks just like Acxede.Net. By the way I didn't have to write any html or javascript for selecting the correct tab, highlighting it, etc. Office Live's built-in events and my stylesheets took care of it.