Samsung's Facebook ads reached 105 million people and generated $129 million in sales

"Everson [Carolyn Everson, Facebook's head of global marketing] offered proof points of the value that Facebook's ads bring from working with Datalogix, a market analytics firm that is measuring how often Facebook's users view advertised products on the site and then make purchases. The data indicated an average three- to five-time return on Facebook ads. A recent ad campaign for the Samsung Galaxy S3 smartphone, amid the iPhone 5 frenzy, resulted in an even larger return on investment. The three-week campaign reached over 105 million unique users, and generated $129 million in sales, a 13-times return on a $10 million ad buy, she said. Samsung now has more than 20 million fans on Facebook to market its messages."

Source:  Cnet, 27th November 2012

Note - This is Facebook's version of events; it's likely that Samsung also used other media, point of sale etc...