In his TV special Real or Magic, David Blaine performs an amazing card trick on Harrison Ford. First, he makes a card picked by Ford disappear from the deck. Blaine then asks Ford to pick a piece of fruit and cut it. Harrison is shocked to find his card inside. It's a great illusion. Harrison Ford is so shocked that he tells Blaine to get the hell out of his house!
You can see the whole trick here:
The first part of the trick relies on some luck on Blaine's part. He hands Ford a deck which only includes a few different cards, each repeated many times. Blaine only picked the cards people don't usually think of when you ask them to think of a card. He still needs a bit of luck, but not a lot. He can be pretty sure that Ford will think of some card that is not in the deck.
Blaine then asks Ford to pick a fruit. This choice is really free – there is no card in the lemon. Blaine has every card already rolled up and can get it into his hand with no problem. After Ford tells him the card he was thinking of, Blaine quickly gets the correct card into his hand and then starts to cut the lemon (note that he doesn't let Ford cut the lemon himself). He uses sleight of hand to put the rolled card inside the lemon and create the illusion that it was there all along. He lets Harrison Ford take the card out and smiles, because he knows the trick is over.