It'll all be for nothing if they don't get Harper Lee. Hurry guys, or you'll miss your window! She's like a hundred!

From what I understand, most of them approached the show and asked to be on. The Simpsons has a surprising number of fans in the literary world. In fact, they rarely go looking for guests because they're constantly being asked by all manner of celebrities. It's been that way since about the third season (the turning point was probably when when Jacko asked to be on.)

5 for Xenocide's Harper Lee exploitation action.

I will find a way to work "she's like a hundred!" into conversation today. Also: I love the question mark on Pynchon's paper bag. They could've just gotten away with the bag, but the question mark makes it.