There's also a little known feature of the English language called flat adverbs: Merriam-Webster Online
Wow, this is awesome! "Ask the Editor".... great for us grammar nerds.
This is an alternate explanation for the Apple campaign "Think Different". I guess it was a flat adverb after all. I always thought that "Think Different" meant that you should think about the state of being different, or think about difference as a desirable approach to the world (sort of like "think snow" at a ski resort). People said it should be "Think Differently", but that has an entirely different meaning - that you should change your thought processes, which wasn't what I took the ad campaign to mean.