I love going and hearing him speak at a signing. This was the third signing of his I'd been to, but only the second where he actually spoke prior to signing the books. He's just that entertaining. (What other author do you know who tells you to go to a restaurant and when the waitress asks if you have any questions, ask "In the end of Star Wars, why didn't Chewbacca also get a medal?")
One thing that really struck me, and I think that he mentioned it in the last signing of his I went to as well, was the idea of a narrative dare. In talking about his writing process, he says he always tries to start with an idea, a what if. That's the dare.
Then he challenges himself to create the world in which that dare is feasible and even inevitable. If you read The Eyre Affair you can see it. His heroine, Thursday Next (isn't that a great name?), is a police officer over literature. Then Jane Eyre goes missing from the pages of the book.
That's the narrative dare, what would happen if a famous literary figure went missing. (At least, one of the dares as I perceive them.) So then he had to create a world in which it would be devastating if this happened, where it could happen, and where the resources might exist to fix it. That's what he means by creating a world where the dare is inevitable.
I'm not sure if I've quite nailed the concept in my own writing but I think I'm getting there with the book I'm currently working on. Only time and beta reads will tell that much. How about you? Do you have a narrative dare that is the influencing factor of everything else that comes into the story?