When I went downstairs to refresh my cup of tea I found The Daughter and The Younger Son setting up Settlers of Catan, so I stayed to play. We don't abide strictly by the rules, but we really like this game as we've adapted it. I bought it at MidSouthCon several years ago.
Here's a video review from TheDiceTower.com that shows the game as it is set up and provides a general overview:
RPG.net has a review, calling it "a landmark game" and saying "it belongs on every board gamer's shelf. It really shines as a gateway game or a game for more casual players because of its core simplicity and its high replayability." Wired.com calls it a "Monopoly killer". Games Magazine has added it to their Hall of Fame.