Understanding MVC in PHP (477 tags)
The most popular "proper" way to build a web application seems to be to use the Model-View-Controller design pattern. While it sounds complex, the concepts are sound and the ease of development it provides are compelling. Joe Stump shows how MVC can work in PHP by walking through working, example code.
The PHP Scalability Myth (123 tags)
Java scales ... but so does PHP. That's the argument Jack Herrington puts forth in comparing how each can be used to create web applications with modern architectures.
The Dynamic Duo of PEAR::DB and Smarty (53 tags)
It can be difficult to separate business logic and formatting in PHP. There are several good templating solutions, though, including the popular and powerful Smarty. Joao Prado Maia demonstrates how to use Smarty with a database back end through the PEAR::DB library.
PHP Form Handling (43 tags)
If your PHP program is a dynamic web page (and it probably is) and your PHP program is dealing with user input (and it probably is), then you need to work with HTML forms. David Sklar, author of Learning PHP 5, offers tips for simplifying, securing, and organizing your form-handling PHP code.
Very Dynamic Web Interfaces (39 tags)