IntelliJ IDEA is very helpful to me ever since i started writing in Java. Yet i work as a PHP-guy and could not find any refactoring-capable PHP editor. I was a bit upset but then decided to write a plugin and that's what's currently on.
The current version has class completion and resolve, go to class action and variable completion as well as syntax highlighting and validation.
Next release will include basic methods resolve and completion.
A lot of other features are planned and if you want to see them soon (and you know Java and have IntelliJ IDEA) - you're welcome to contribute!
If you want to tell me something, send feedback, contribute or whatever, please be sure to write to firstname.lastname@example.org