Server / filename manipulation

Hi, I have an question on how to create a completely database / xml driven site i.e. the page names, links, the site map etc are held in the database. I think I have solved most problems but what I would really like to do is limit the number of pages I need. Can I manipulate the server such that if I have links to a pages; <a href="red_hats.php">red_hats.php</a> and <a href="yellow_hats.php">yellow_hats.php</a> can both these links and others link to a different page that dynamically constructs whilst the links aren't altered. Maybe is there some way that a default php page is called that reads the link of the page called and constructs appropriately etc. I would be most grateful for your input on this.