There are countless variations to this game. For my game, properties can only be developed once they are all sold out. Hence the landing on a property at the beginning is crucial to the development of the game and this is heavily depended on luck. When they are no properties left to buy, the trading phase will begin. At the beginning of a player's turn, he is only allowed to trade with one person. He has 30 seconds to offer his proposal to the other player and that player can only accept or reject the trade without any alterations to the proposal. This stage is heavily depended upon the negotiating skills and common sense of the players as 'whoops' happens from time to time throughout the game. My advice in trading is always make a trade the other player cannot refuse. By doing so, you can blind the other players with their short term greed. Another important factor is there is no trade without losses and risks. For those players who only want to make trades in which you will be the single benefactor, good luck with that as your game will be the desperation of everyone else, including you. Another version is the Lord of the Rings Monopoly where the player steps on the property with the ring on it will either get that property for free, or pay double the rent. I actually won this game with only owning the most expensive property (the dark blue one) and the leading player landed on it twice in a row with the ring there. Talking about snatching victory from the jaws of defeat.
To spice this game up, we can have the losers paying for breakfast, every player putting 5 bucks into the game, playing this game the adult game or any other combinations. In Strip Monopoly, any player can trade in their clothes anytime during the game for 500 dollars a piece. Once that player runs out of no alternative, then it would become a 'dare' activity. This will definitely prolong the game as it makes going bankrupt a lot more difficult. Of course, the only thing more depressing than being naked in winter without heater is losing within 30 minutes in a 2 hour game.
Thankfully, the Germans are coming to the rescue with the creation of nonzero-sum boardgames. Board games that promote conquest and killing are apparently banned in German. However, one can still liberate other players. I just found out about this game called Settlers,http://www.wired.com/gaming/gamingreviews/magazine/17-04/mf_settlers?currentPage=1 , and apparently it's a very big hit in Europe. Hopefully there can be many variations to this game. Else, ordinary college students will not buy it.