$6B - 'B', Like in BRAINSThis WSJ 24/7 article is about a year old (whoever said BIC wasn't on the ball?) and guesstimates the zombie economy at around $5.74B. But that's a year old & the article only goes down to grade B movies & doesn't address grades C-Z or even porn or the crazy Japanese stuff. Interestingly, the article points out:

George Romero’s 1968 cult classic Night of the Living Dead is royalty-free, and does not add much to the actual economics of the zombie genre.

For Porktown gore fiends we can look forward to bloody Milford's Horror Hound's convention at the shiny Sharonville Convention Center in March (when the ground starts to loosen up a bit) to add our share to the zombie economy.