Timothy Boronczyk has a recent post to his site with an interesting thing to use PHP for - composing music.

I'm not an expert on probability theory, artificial intelligence and machine learning, and even my Music 201 class from years ago has been long forgotten. But if you'll indulge me for the next 10 minutes, I think you'll find that even just a little knowledge can yield impressive results if creatively woven together into an application. I'd like to share with you how PHP can be taught to compose music.

He shows examples of some basic melodies generated by PHP (not the prettiest) and talks about how he "taught" PHP to get better at it. He transcribed other music into Scientific Pitch Notation and used a Markov process to create a "next note selection" method based on the notes around it. He includes the code for his "robot composer" class with its "train" and "compose" methods and and example of its usage.