A friend of mine once made a "Dungeons and Dragons Monopoly" variant where each character was a D&D class and the spaces were re-named as iconic D&D locations. If a character landed on the same space as another, they'd then get to "fight" (roll two dice and compare numbers) and the winner could steal a property from the other. It turned out to be one of the more fun Monopoly variants I've ever played, as it allowed monopolies to be created easier (fighting to get that third property someone wouldn't trade you) and thus the game progressing faster.