From the fertile mind of Andrew Domino comes Monster Menace Monopoly:
All you need for Monsters Menace Monopoly is a copy of the World’s Most Popular Board Game (I don’t know if that’s trademarked, but it feels like it should be). Tired of spending hours going around and around the board buying and selling properties? Why not spend some time going around the board throwing houses and hotels at the other players, and stomping on Boardwalk? These are links for the Monsters Menace Monopoly (PDF format) rules, the monster information sheets (PDF format), and player tokens (PDF format) which you can print and cut out.