When Mark Zuckerberg was featured on the Inc. 30 Under 30 list in 2006, he was 22, and Facebook, the social network he co-founded from his Harvard dorm room, boasted seven million registered users. Rumors swirled he was holding out for a $2 billion buyout offer.

When Facebook went public this May, the site had skyrocketed to more than 900 million users and was worth a staggering $100 billion.

The Inc. 30 Under 30 can be the launch pad for the big leagues. 

Just weeks before Facebook's IPO, Zuckerberg agreed to pay $1 billion for Instagram, a photo sharing app developed by Kevin Systrom and Mike Krieger, 30 Under 30 alums from 2011. Though Instagram was not yet making money, it was giving Facebook a run for its money--on mobile social networking. Indeed, since being profiled on the 30 Under 30, the Instagram founders say they've grown their user base nearly sevenfold to 27 million.

Plenty of other 30 Under 30 alums have recently been rewarded with sweet exits. Ryan Allis and Aaron Houghton (2010) sold their email marketing company, iContact, to Vocus in February for $169 million. The Cook siblings--Catherine, Geoff, and Dave (2007)--sold their myYearbook website last summer for $100 million in stock and cash to West Palm Beach, Florida-based Quepasa, a social network that caters to young Latin Americans. For undisclosed financial terms, the Foodzie team--Emily Olsen, Rob LaFave, and Nik Bauman (2009)--sold the online food marketplace to Joyus, a video shopping start-up, and Sarah Prevette (2010) sold Sprouter, her start-up advice website, to Canada's Postmedia Network.

Despite the lackluster economy, Inc. 30 Under 30 alums are also raising capital. In June, Matt Lauzon (2011) of Gemvara raised $25 million in a Series D financing round to improve the customized jewelry site's shopping experience, and Adam Goldstein and Steve Huffman (2011) raised an additional $15 million for their travel site, Hipmunk, to double the staff to 32 over the next several months. In May, David Gorodyansky and Eugene Malobrodsky (2011), the founders of AnchorFree, which makes the Hotspot Shield for secure Web browsing, raised a $52 million Series C round from Goldman Sachs. 

Many of our 30 Under 30 alums are plugging away, pivoting, and otherwise gunning for growth.

Adam Sachs (2011), co-founder of Ignighter, says that "after nine months of intense branding and positioning work involving focus groups, user surveys, we've rebranded for the Indian market. We're now StepOut.com, India's No. 1 place to meet new people." The company recently crossed the four-million-user mark and started monetizing, and says it is seeing 300% growth over the past few months. 

The Shirt, founded by Rochelle Behrens (2011), is no longer just the shirt. The company launched an entire 150-piece clothing collection using the same dual-layer technology, and moved production from Spain to New York City's garment district.  

The Second Glass (2010) founders, Morgan First and Tyler Ballet, moved operations from Boston to San Francisco and expanded their Wine Riot events to Chicago, Los Angeles, New York, and Washington, D.C. The company now works with 350 wineries (up from 12 when the founders first appeared on the 30 Under 30) and is producing a mobile app for iPhone and Android. Meanwhile, Nick Friedman and Omar Soliman (2008) report that College Hunks Hauling Junk has grown fourfold since being featured on our list and has launched a full-service moving company called College Hunks Moving. The company now has 40 franchisees who employ over 600 employees. 

Who on this year's list will be the next Mark Zuckerberg?