Other noteworthy trends include a 21% jump is U.S. media sales to $4.15 billion. The company also said it is adding 17 new fulfillment cents in 2011, compared with its prior plan of 15. "We note that Amazon has been through various reinvestment cycles in the past, which have dampened near-term margins," Credit Suisse analyst Spencer Wang wrote in a note. "However, given the attractive growth prospects and the high ROIC characteristics of Amazon's business model, we think this is the right long-term investment decision. Ultimately, we believe value creation is driven by increasing profit dollars as opposed to profit margins. Amazon has employed this strategy in the past to much success." Amazon is typically tight-lipped during its conference calls and last night was no different. Chief Financial Officer Tom Szkutak drove home Amazon's message about "lifetime value." "And when we think about the economics of the Kindle business, we think about the totality. We think of the lifetime value of those devices," Szutak said. "So we're not just thinking about the economics of the device and the accessories. We think about the content. We are selling quite a bit of Special Offers devices, which includes ads. We're thinking about the advertisements and those Special Offers and those lifetime value s ." The hope is that Kindle Fire users will ultimately be more active Amazon shoppers. Kindle Fire users will receive one month free of Amazon Prime, a tactic used to get more people to sign up for the $79-a-year service. Amazon Prime members receive free two-day shipping, as well as access to about 12,000 (and growing) streaming movies and television shows. Currently, Amazon Prime boasts about 12 million members who buy four times more merchandise from the e-commerce giant than the regular shopper, according to ChannelAdvisor, an e-commerce business software firm. Bank of America Merrill Lynch analyst Justin Post estimated that an active Amazon shopper spends about $115 per year on media and that tablet users will spend about 50% more on books, movies, music and games. This could add about $60 a year in annual media sales per Fire customer.