In January 2011, Portland’s Microcosm Publishing bookstore started offering customers store credit equal to the full retail value of any Kindle they bring in.

Around the same time, Amazon launched its 'Singles' e-books.

In the 14 months since the format's launch, Amazon has sold 2 million Singles. The 165 Kindle Singles titles, e-books with word counts of between 5,000 and 30,000 and prices between USD0.99 and USD2.99, are doing well partly because of their prominent marketing on Amazon webpages.

"If you're on that list, it's a lot easier to get noticed," says Kindle Content VP, Russ Grandinetti. Kindle Singles include short stories, novellas, journalism, non-fiction and opinion pieces, and are available solely for Kindle devices.

Paid Content's Laura Hazard Owen crunched the numbers and said that "with an average price of $1.87 multiplied by two million, a rough estimate of Amazon’s 30-percent cut is $1.12 million." Not huge huge, but a nice figure.

Singles authors pocket 70 percent of the sale, one has reportedly earned $130,000 in royalties.