Company: Reddit

Position: Co-Founder

Alexis Ohanian may be more known for his work as an Internet activist and entrepreneur, which is surprising when you realize he co-founded Reddit, one of the most influential social sites on the web. The Brooklyn-based techie was named one of Fortune's "30 Under 30" and is currently working on a book--Without Their Permission: How the 21st Century Will Be Made Not Managed--that is sure to cause an uproar.