Steam is essential cracked within hours, it's almost a non protection now I think. I read an interesting article once, the lines of which basically said that if your a small dev and someone cares enough to crack your game, it's almost a good thing....it was written by a solo dev who released a game no one bothered to crack. Lol. I guess what they meant is don't worry about copy protection until your big enough to need copy protection - if your game is good enough to play it's good enough to buy, so use advantages and bonuses to promote that.
I think for the best copy protection you should add code though......GTA 4 and the constantly drunk mode every second load? Batman and the impossible jump (on a pirate copy the game was fully functional, except one crucial jump was made wider and impossible). Or the king.....game dev tycoon: pirate the game and no matter what you do, eventually in your game pirate downloads will drive you out of business. Lol.