For my own phone forwarding system, SMS messaging, and will gladly build such systems for clients.
For bells and whistles on the UI, and for making the game Whack-A-Mol. I purposely avoided jQuery or other 3rd party frameworks, as I was aiming to make a low overhead website system, rather than a complex web application like I make most of the time.
To generate websites from data, and to serve my UI for defining that data. Also many small personal tools, such as icon converters (rather than bash scripts). PHP is my go-to tool for server side logic.