splash Masque Clear Screen Protector for iPhone 4 4G  4S AT&T and Verizon (3-Pack + 2 Bonus Back Films)
It was easy to apply and looked nice, but as soon as I put my case (ifrogz) on, it buckled on the top and bottom.  I tried a few different ways, but I was unable to get both the screen protector and the case on.  Maybe it will work with a case that doesn't fit so tightly?