One Card Brainwave
Effect as advertised: You hand a deck of cards to a spectator (telling him to put it behind his back) to remove a card from somewhere in the deck that he decides on, have him turn it face up on the top of the deck, and make one complete cut. The spectator then hands you the deck. With all eyes watching you, spread the face-down deck (one card at a time) until you come to the face-up card (which is removed still face up), and continue to spread the deck right down to the bottom card—proving one and ONLY one card was reversed in the deck. Next, the face-up card is turned over and shown to be the ONLY card with a back design different from the rest in the deck. The deck can now be examined and used for other effects.
The effect is explained in Dusheck's Card Magic, page 37 (1992)