John Swartzwelder is, as the cover of his books say, the author of 59 Simpsons episodes. He stopped writing for the Simpsons in 2004 and started writing these books (though he was back to write on the movie). I'm sure most people will find their way to these books from the high praise they get on the commentary tracks to the latest few Simpsons DVDs, as I did.
There is a piece of the commentary for season 10 where the staff says that John Swartzwelder can get them to keep anything in the script, no matter how ridiculous, by prefixing it with "for some reason" (a gunfight breaks out between the cowboys, for some reason, one starts digging a hole). I'd say something like 1/5th of the humor in these books comes from something similar–a little tag at the end of an otherwise cliché sentence.
Anyway, the books are short and not too expensive, so I'd say start with The Time Machine Did It and work your way up. He's writing about 1 a year, if you include the non Frank Burly Double Wonderful.