Social networks have long had the ability for people to point out what they like, and to pester their friends with this information. Why? Partially for social reasons, people like to be with people that enjoy the same things that they do. But now, Business magazine Forbes reveals that there's a cash value associated with this.
Someone clicking an "I like this" button on a social network is worth $136.37 to a marketer. This number comes from estimations on how much more of something a fan buys vs. a non-fan, how often they tell their friends (the ever famous "viral marketing" that has many marketing firms violently salivating), how loyal they are (so that they don't switch to the competition just because the competition gave a minor discount), and how likely they are to buy again. All of these are factors that marketers pay out the nose for.
Of course, the only difference since social networking is that now this is obvious, even blatant, and public. Before, companies might have noticed that some people were more vigorously pleased with the brand, bought it more often, and so on, but now people are practically putting a little badge indicating their fan-dom.