PHPit.net has posted yet another fine tutorail today, this time discussing the creation of HTML widgets with the help of PHP.
In this tutorial you'll learn how to create your own HTML widgets, using nothing more than PHP. You'll be shown how to use an output buffer to create your own HTML tags, and then replacing them with dynamic content. The tutorial will finish by showing you how to create a Repeater Control.
They start with an example of using an output buffer callback, a precursor to making your own HTML tags. It grabs the tag from the page, parses it out to perform an action, and spits back out the result. He also implements an HTML parser (one of his own) to correctly parse out the (correctly formatted) HTML into a PHP array. From there, it's just a simple matter of defining your own HTML tags and outputting the custom result inside the handler.
Finally, they get to the Repeater control, a method for displaying the results of the "HTML in PHP" array with all of its custom-tag glory.