If you're a fan of the Textmate editor for the Mac platform, you might want to check out this new post from the cssgallery website. It shows how you can get your favorite editor to check your PHP syntax for you.
A nice "hidden" feature that Textmate has, is to check the syntax of the php files you are writing, and display a popup with the result. [...] Each time you save, a syntax check will be done, and a popup will show you the result
You'll need to edit the PHP bundle slightly to get things working, but that's as easy as going through the UI and changing a drop-down value to activate the check. You'll need to have a php binary where the editor can use it, but most OS X installs will have that in place anyway. Check out this image to see the end result.