Goodreads, the online social community focused on book readers, looks to be on a roll. The Los Angeles firm, which is run by Otis Chandler, reported this morning that it now has 10 million members, only three months after hitting the 9 million member mark. The company said it took four and a half years for the site to hit its initial, five million members. The site did not say why it's seen a huge uptick in members, however, the company's services are now heavily used in libraries, social networking sites, and more to see user reviews of books, for looking up interesting titles, and discussion books with others. Goodreads said that its members have "shelved" more than 360 million books, meaning those readers have either marked them read, shared reviews, or added them to a list.