Worried about all the time you're spending on Facebook? Well, what if your wasted time was actually making money for St. Jude's Research Hospital or another charity?

That's the idea behind GamesThatGive, a San Francisco-based startup founded by former Apple software engineer Adam Archer and web developer Kris Goss. Facebook software company Vitrue just closed a deal to buy the company, and will integrate its capabilities so brands will be able to create charitable games on their Facebook pages. The deal price was undisclosed by GamesThatGive has just six employees in San Francisco.

Vitrue made news a few months ago after grabbing $17 million in a third round of funding and getting an A-list adviser: Mike Murphy, former global ad sales chief of Facebook and current senior adviser to casual games giant Zynga, which recently filed a billion-dollar IPO. Vitrue tools are being used by brands such as Procter & Gamble, AT&T, Nascar and Coors as well as agencies such as Wieden & Kennedy, Y&R and Edelman.

"It's guiltless gaming," said Mr. Archer, who co-founded the company in 2008 and will become general manager of games at Vitrue. "Our goals are for brands to achieve their marketing objectives."

For every minute that fans play charitable games on brand pages of companies such as Domino's and Dockers, brands donate money to charities, including Ronald McDonald House, American Heart Association, Unicef, St. Jude's Hospital and The Breast Cancer Fund.

While it's no "FarmVille," the Domino's "Memory Game" has had almost 500,000 minutes of game play and GamesThatGive said that many of its players average 40 minutes of game play per visit and each player invites more than one person to play.

"As a partner of both Vitrue and GamesThatGive, we can easily manage our entire social presence in one place, and not only acquire and engage with fans in ongoing, innovative ways but also tie-in our charitable foundations in a seamless manner," said Russell Weiner, chief marketing officer, Domino's Pizza.

So go ahead, waste some time on Facebook -- it's for charity.