Seattle-based online retailer Amazon.com has purchased fellow Seattle firm Shelfari, an online site focused on books and social networking. Shelfari announced the acquisition on its blog Monday evening, but did not disclose terms of the deal. Shelfari was venture backed by Amazon.com and Curious Office Partners. According to Josh Hug, President of Shelfari, the firm has some "big plans" ahead and will use more resources and Amazon's expertise in building its platform. No other details on the acquisition were released.