Talk about having some wealthy friends. Six people involved with Facebook made Forbes magazine's 2011 Billionaires List.

Facebook co-founder Mark Zuckerberg is at the top of the richest social networkers with an estimated $13.5bn (£8.4bn), according to Forbes. Zuckerberg had a good financial year, with his wealth jumping 238 percent in the past year.

And Zuckerberg isn't alone. Company co-founders Dustin Moskovitz, Eduardo Saverin and Sean Parker also made Forbes' billionaire list.

Moskovitz, the world's youngest billionaire, was Zuckerberg's Harvard roommate and Facebook's third employee. Today, he's worth $2.7bn.

And Saverin, who started Facebook with Zuckerberg while they were in college, had a falling out with Zuckerberg - there was a lawsuit and counter-suit involved. The parties settled and Saverin is now worth $1.6bn.

As for Parker, the former Facebook president and co-founder of Napster is also worth $1.6bn.

Facebook's final billionaires are Peter Thiel, co-founder of PayPal and a Facebook investor, worth $1.5bn, and Yuri Milner, who has invested in Facebook, Groupon and Zynga and is worth $1bn, according to Forbes.

Lest the folks at Facebook think they have a lock on all the social networking billionaires, Groupon and Zynga added a few names of their own to the Forbes list.

Mark Pincus, who founded social gaming company Zynga, is worth $1bn; and Eric Lefkofsky, co-founder of online discount provider Groupon, is reported to be worth $1.6bn.

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