Fifty Shades of Grey by EL James

Right now, the most popular non-Hunger Games book series in the country is Fifty Shades of Grey, a trilogy of explicit erotic novels that features lots of dominance and submission. The series started humbly self-published and was recently acquired for seven figures by Random House, which thinks it has the potential to become the next The Girl With the Dragon Tattoo. And if sales sustain themselves, they could be right.