When uploading images this handy PHP extension will allow you to manipulate images on the fly - resizing, renaming, change format and even add effects.
Generate PDF's on the fly based on the content of your MySQL database.
Generate Excel files on the fly based on the content of your MySQL database.
Go beyond the simple PHP
Not PHP but what the heck if you want a robust HTML formatted email that will work across all those pesky mail clients, phones, tablets, fridges then Zurb have these handy templates.