You can do a lot with a deck of cards. You can play games, throw them, perform with them, and even make a top hat.
One of the most popular card games is Solitaire, included with every copy of Windows. This game is generally played alone, unless you have spectators, then you're playing alone with people watching you. With this Instructable, I will show you how to cheat at this game. Note that I did not create these myself. I do not know who did.