" In Friendster's wake, a throng of social networking sites blossomed in San Francisco attempting to duplicate its appeal. Each tackled the idea of connecting people in a slightly different way. One was Tickle, a service which, on observing Friendster’s broad-based appeal, altered its own service, which had previously been based on self-administered quizzes and tests. Two of the other new social sites—LinkedIn and Tribe.net—were founded by friends of Abrams. "

― , The Facebook Effect: The Inside Story of the Company That is Connecting the World