One of the cool things that I switched over to when I created this new version of the site was an array-based naivgation system. The bar that you see to the left with the selections for the "Main Menu" is actually created from an array of values, and is made on each page that you load. This allows for a bit more flexibility as far as choices, and adding a new section is as simple as adding a new value set to the array.

Zend.com wants to take that one step further and show you how it's done. In Side Navigation with PHP, they start you off simple, but jump into the meat of it all pretty quickly. Their menuing system has more than one layer (unlike mine, which is a bit simpler) and would allow you to have subsections on your site easily. They give you all of the code for the layout and construction of these menus, as well as visual examples of what the output looks like.

This system could be used for anything from a simple static layout like we have on this site to something more ornate with DHTML menus and drop-downs, all generated on the fly - either from a hard coded PHP array, or from a database somewhere that contains a parent/child relationship for the categories. This could save immense amounts of time for adding new sections to a large content-driven site.