10. Matthew Charles Mullenweg – WordPress
Photo from: Business Week
At the age of 19, this native Texan founded WordPress, the free and open source web software that powers 15% of the web. Despite having dropped out of the University of Houston and never receiving a degree, Mullenweg is estimated to have a net worth of $40 million. Not only is he renowned as an innovator of open source technology, Mullenweg actively supports several charities and is an expert at the jazz saxophone.