Arkham City. That'd just be tops. Unfortunately, we don't live in Australia, where the EB Games-exclusive "Steelbook Edition" comes with the blue-tinged DLC, along with a few more bat-themed goodies.
Buyers of the "Steelbook Edition" also get their game in a fancy metal box, access to the "Joker Carnival" Challenge Map DLC, and a copy of the "Batman: Under the Red Hood" animated film on DVD (or Blu-ray, should you buy the PS3 version). And for $98 AUD ($107 USD), they'll be paying exactly the same price as Aussies buying the regular edition at other game retailers.