The Official Monopoly game. With Oddworld. The Oddworld part isn't official, but the monopoly sure is. Make your own Monopoly is the perfect way to have an Oddworld Monopoly game.
Xavier was talking about this months ago, so here you go. The best way to make Oddworld Monopoly:
http://www.boardgames.com/makyourownmo.html
(Just a random website)