The Darksiders home page
is teasing that the initial run of the game will include a code for something special. They aren't saying what it is yet but if you were thinking about picking up the game, this week might be the week to do it. I really enjoyed
the game and I'm guessing a lot of people out there will as well.
I'm not sure what it is (I'm guessing it's an in game item or some minor form of DLC) but it does show that developers and publishers are looking for new ways to help fight against the "issue" of used games. We'll let you know when we find out what the item is.