With social networks now big business, what can the companies do to turn free services into hard cash?
Over the past month, US Facebook users have been enjoying a selection of Warner Bros blockbusters streamed through the site in exchange for about $4 (£2.45) in Facebook credits.
Facebook takes a 30% cut of each credit spent, much like Apple and its app store.
There are over 400 apps and games where the site's 500 million users can go on a social spending spree.
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How can social networks make money?