In Photoshop CS6, the new version of Photoshop, you can use special cropping tool and you are done, but that doesn't mean you cannot achieve the same result with older versions.
Fun, yet very useful tutorial, where you manipulate a photo in a way it will look like you're standing next to Brad Pitt or any other person in that matter.
Not your average pixel effect tutorial, let me show you a nice little trick where you apply the normal square pixelated effect and turn it into checkered, diamond looking photo pixels.