It’s not exactly in English, but it doesn’t really matter. There is an official Simpsons Firefox theme promoting the movie.
// Image lost. Sorry. Zooomr ate it. //
Sure, it’s a German theme, but it contains doughnuts and The Simpsons Movie logo.
I had thought of creating a Simpsons theme once, but it would have been much more character orientated. Still, it’s kind of fun and looks decent. Not enough Simpsons for me, but the doughnuts look tasty.
Download the theme from the official Mozilla Addon site.