Court Jesters by Peter Kane
I'm a sucker for packet tricks, and this is SUCH a good one. The effect is crystal clear - you have four red backed jokers, and one at a time, they turn blue backed. Simple, clear and visual magic.
What sets this apart though, is the construction and the method. There's no rough and smooth, no sticky stuff, or extra cards - you can just slip the four cards in your pocket or wallet, and with just some basic card moves, bust out a great piece of magic!