There's a lot regarding Pinterest's growth on Quora. For starters, see "Which viral concepts is Pinterest getting right that may be enabling their staggering

There's a lot regarding Pinterest's growth on Quora. For starters, see "Which viral concepts is Pinterest getting right that may be enabling their staggering growth?" http://www.quora.com/Pinterest/Which-viral-concepts-is-Pinterest-getting-right-that-may-be-enabling-their-staggering-growth http://www.quora.com/Pinterest/Which-viral-concepts-is-Pinte... and "Why did it take so long for Pinterest to go viral?" http://www.quora.com/Pinterest/Why-did-it-take-so-long-for-Pinterest-to-go-viral http://www.quora.com/Pinterest/Why-did-it-take-so-long-for-P...