PHPBuilder.com has another excerpt from the book PHP 5 in Practice showing quickly this time how to create a dyanmic progress bar for your application.

In some situations you might need to display a progress bar—for example, when you are performing many tasks on the back end and they take a while to complete. In these cases it is a good idea to give some indication to the user that you are in fact still performing tasks and that their browser hasn't simply locked up.

They demonstrate a few different ways to accomplih this task including a simple "Please wait" kind of message and a more PHP-based example that changes the width of a DIV based on the amount of time it's taken to perform the task.