Most sites requiring registration ask you to choose a "secret question" to which only you supposedly know the answer. Of course, in the age of Google, the city where you were born and your mother's maiden name may no longer be the best kept secrets in the world.Link (Thanks, Merlin!)
So, next time you register for a site and it asks for your response to a challenge question, choose something that's completely insane, but really memorable to you.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.