According to e-Marketer, global social networking revenues will exceed $10 billion 2013. Most social networking sites like Facebook, Twitter, Tumblr, and many others offer their services to members for free, yet still net significant income. In fact, according to Mashable Business, Facebook earned $1.6 billion in revenues in the first half of 2011, and was on pace to achieve more than $3 billion in revenues by year end.