Joe Green is most likely the Facebook roommate you've never heard of, but the Harvard graduate is trying to make a difference in the world, with friends.

Green lacks the name recognition of company co-creator Mark Zuckerberg , or even Eduardo Saverin, who famously helped launch Facebook, although he was there with the Internet entrepreneurs in that dorm where the social media powerhouse was born. And he walked away from it.


No regrets: Joe Green

Green was one of Zuckerberg's roommates at Harvard University in 2004, and was asked by the young man to join him in building the social media website, which is expected to file for an initial public offering this week.

After the two had gotten into some hot water with Harvard for a previous project -- the hot-or-not website Facemash, -- Green ultimately told Zuckerberg "no" because the school had threatened him with expulsion.

His decision not to join Zuckerberg could now be considered a $400 million (Rs 1.991 crore) mistake. "We'd gotten into a little bit trouble with the previous project... and my father, who's a professor, was not too happy with the prospect of me getting kicked out of school," said Green.

Now, despite his initial decision, he's back in the Facebook fold, running a for-profit business called Causes, a Facebook application and website that lets friends suggest to friends a charity, social cause and even political candidate.

Green, the roommate who said "no" to what became a Web behemoth, has no regrets, although he does have plenty of Facebook stock, and he's found his own cause.