It's natural to assume that NetBeans is an IDE focused on Java since it was built by Sun. But the NetBeans creators are also distributing a version focused on PHP.
It still has plenty of Java-centric tools, including a profiler that wants to know whether I want to instrument the basic Java classes too, but there are plenty of other features for the PHP developer, including the standard colouring and code completion.
PHP editing works right out of the box, but testing takes a bit of configuration. I was able to get the IDE working with the classic WAMP distribution only after several trips to the php.ini file. NetBeans includes several hints for editing php.ini that appear when the debugger fails to connect after a few seconds.
PHP debugging is fully integrated with the IDE. If you drag your mouse over a variable name, it will post a balloon with the type of the variable and the value in it if it's a short one like an integer. A right-click will take you to the definition of a function.
If you're a developer looking for a full IDE, it's pretty much what you want to see.