#6 Juliette Brindak

Juliette Brindak, at the tender age of 10, started a social networking site for tweens known as Miss O And Friends. It generates 10 million monthly visits, a twenty-fold increase from its inception in 2005. It's also worth around $15 million, according to early investor Procter & Gamble, reports Business Insider.

Brindak drew characters for a set of five friends she called “Cool Girls," who were all inspired by real-life girls. The main cool girl, Miss O, was her younger sister Olivia. The set of "Cool Girls" would eventually become "Miss O And Friends."

What started out as a few sketches on the way home from a family vacation quickly ballooned into a haven for millions of adolescents. The site was ranked the third largest girls-only Web site in 2011, according to Inc. Magazine.

Read Also: WhatsApp Is Bigger Than Twitter, Claims CEO and Microsoft Signs Android Patent Deal With Taiwanese Company Foxconn Parent