And if you need some inspiration, here's all of our costume galleries from the past two BlizzCons and the results of last year's ingame contest. Sure, you probably can't beat that girl on the turtle (or can you?), but as the couple and their adorable baby Murloc above show (they're from Blizzard's official gallery from last year), even a little bit of costume goes a long way.
Gallery: Hallow's End Costume Contest
Gallery: BlizzCon 2008 Costumes
Gallery: BlizzCon Costumes