The Settlers of Catan is a relatively new game in the boardgame world, but has become a must in my household. There are so many variations and twists in the game that, unlike monopoly, it is never the same. The best part, it's really easy to learn, but amazingly hard to master. This means hours of fun for the new player, but also many hours of developing new strategies for the more experienced. With each expansion the game develops more layers, and changes the play style to such an extent that almost anyone can find a version of the game that will suit them.
Excellent game. 5 out of 5 the only down side is the actual board, which is made from very thin cardboard, and does not slot together as solidly as I would like.