McGuffins. McGuffins Everywhere!

Have I got a warehouse for you!An online discussion about McGuffins prompted this article.
Whatâs a McGuffin?  McGuffins are the things that makes the characters do things.  The late, great, Sir Alfred Hitchcock, who popularized the term, defined it as such:
It might be a Scottish name, taken from a story about two men on a train. One man says, "What's that package up there in the baggage rack?" And the other answers, "Oh, that's a MacGuffin". The first one asks, "What's a MacGuffin?"...