"The Simpsons," which airs its 500th episode tonight, also boasts another record: "'The Simpsons' hits a milestone Sunday with its 500th episode, but it has also quietly managed to break another record en route: the most original musical scores ever composed for a primetime series ... Alf Clausen has written 483 of those 500 scores, starting with the show's first Halloween episode in October 1990. He's won two Emmys and ...