The Developer Tutorials blog has a new post mentioning the use of YAML structure for creating configuration files in your application.
YAML, or YAML Ain't Markup Language, is a "human friendly data serialization standard". It's essentially a very basic format for storing data, and uses far less syntax than standard PHP. [...] It's almost like English; it's as basic as you want. Of course, that's not to say it doesn't support complex structures - this example demonstrates the power of the format.
He also points out the spyc extension that makes working with the files in PHP a breeze.