This simple, effective "crystal ball" illusion is documented by Nikki on Ehow: basically, you put a video loop on your phone's screen, drape it in black cloth, and insert it into a crystal ball, and voila, you've got your own Madame Leota (or whatever video you choose), as seen in the Haunted Mansion at the Disney parks worldwide!
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.