Rapid development of performant get/post web interfaces. Ruby is nice but runs a lot slower. Python is better in a general-purpose sense, but every file will have a preamble of includes for things that are just built-in to PHP.
As a general purpose language, PHP is weak. As a web-form DSL, it's great!
As a general purpose language, PHP is weak. As a web-form DSL, it's great!