2. What do you think of Facebook's new revenue stream model? Will it work? Not too long ago, people doubted the commercial sales potential of bottled water because a perfectly good substitute was available for virtually no cost. At the time, many skeptics made comments like "What's next, are we going to sell air?" Today, consumers purchase approximately 200 billion litres of bottled water worldwide each year. The skeptics did not foresee an era dominated by the internet, smart phones, and social media M. least bottled water is a physical product. But how much is an avatar worth? How much would you spend on a virtual good? If your answer is $0, you don't know what's going on in the virtual gaming world. Have you heard of Zynga? World of Warcraft? Mafia Wars?

FarmVille? H you answered "no" to all these questions, you may be shocked to learn that, in 2010, virtual goods sales were expected to reach $1.6 billion in the U.S.

alone, and are projected to grow to $3.6 billion by 2012.