Unilever see sales of $8.41 for each $1 spent on advertising one range of products on Facebook

"Facebook, which previously only provided advertisers with the number of people who saw an ad on its site, soon gave Ms. Wakeling other data on how many people saw Facebook ads in a variety of areas. Facebook also figured out how many people in a region saw a paid ad versus other types of ads such as print, radio or TV.
The moves meant Ms. Wakeling could begin comparing how many people in one region were exposed to a paid Facebook ad against the number of people in a region who were exposed to a television ad. By comparing campaigns across regions, she could track the success of the ads with any resulting increase in sales in the specific regions. Ms. Wakeling said Facebook was "very collaborative."
Facebook's Mr. Smallwood also ran a series of test ad campaigns with advertisers between last October and this January based on the methodologies they were learning from each other. By April, Mr. Smallwood had conducted 63 such campaigns.
Later in the year, at another Facebook meeting with its Client Council in New York, Mr. Smallwood displayed a chart to the gathered executives. Out of all 63 test ad campaigns, only one campaign had a less than one times return on its investment. The majority showed a return on ad spending of three times or better.
One of the campaigns was for Unilever's Suave beauty and grooming products. Using the methodology Mr. Smallwood developed with Ms. Wakeling, Facebook was able to show that for every dollar Unilever spent on the social media site, the consumer products company got $8.41 back in sales."

Source:  WSJ, 15th August 2012