Well, it’s public now, so I can mention it here, too.
If you pre-order Darksiders: the Abomination Vault, you’ll also receive access to a free code that can be used with Darksiders II to unlock a special weapon that appears in both the novel and the game. 😀
Pre-orders are available at Barnes & Noble and Amazon, for hard copy, Nook, and Kindle. Current release date is May 15th, or thereabouts.