UPDATED 13:46 PM EST, December 5, 2012
Games can be both a welcome and an annoying diversion on Facebook, the world's most popular online social network. This year, Facebook crossed a big milestone — reaching 1 billion active users. Game companies such as "FarmVille" creator Zynga Inc. and Rovio Entertainment Ltd. of "Angry Birds" fame seek to tap into that vast base of users to gain more players for their games.
