Another cool game to play is Acquire.
http://www.wizards.com/default.asp?x=ah/prod/acquire
You place tiles on the board to build up companies that you can then buy stock in. When a tile is place that connects two companies, the one with less tiles is merged into the larger. If you have stock in the smaller company, you can get cash or shares in the larger. If you have stock in the larger, it's now worth more (the stock is valued based on how many tiles it has.) Whoever has the most money/stock value at the end wins. My descriptions probably sounds a bit complicated, but it's really pretty easy to play.