Dynamic Navigation w/PHP

Hello All, I am looking for example code demonstrating the ability to dynamically modify website navigation based upon data in a database. Specifically what I am trying to figure out is how to control what pages are available based upon whether they have been "enabled" in the database. I am developing a template driven website, with content controlled by the database which indicates what the customer has opted for. While ten pages might be available and part of the web site template, a given customer may have only paid for four, thus when his site is hit, only those four pages will be available in the navigation elements. Should the customer care to request an additional feature (page), simply accessing the database and enabling it would make it immediately available. Any suggestions or pointers would be greatly appreciated. Michael