Best known as the cofounder of the social news site Reddit.com, Brooklyn-based entrepreneur/investor Alexis Ohanian shares stories of artists, enterprisers, and civic-minded hackers who have taken the initiative and gotten surprising results. His new book, Without Their Permission: How the 21st Century Will Be Made Not Managed, is a call to action that combines advice and marketing secrets for building successful start-up ventures with heartwarming examples of Internet use for grassroots campaigns.