Another simple way to do this (not specifically for PHP) is to make a template. Dreamweaver definately has this, I do not know about other software. Basically you just make a "sample" page with the link bar and anything else you want displayed on every page, and then you make pages with the existing template. Later, if you want to add/remove a link from the link bar, you only have to edit the template, and all pages using it will automatically be updated.