http://www.enthrill.com is providing an incredible service for both authors and traditional retail book stores.
Through enthrill, authors can purchase digital codes or a combination of digital tracking codes packaged with a print pre-paid eCard of their book. It looks like a mini version of your book, but it is a card that activates a digital download of the book. Which is able to be used on a range of devices. So the consumer can purchase once and use many times on the range of their personally registered devices (iphone, ipad, kobo, kindle, etc).

This way authors at speaking events can sell a digital version of their book, fully activated and ready to go for the customer, and it is something ‘in hand’ that can be sold on the spot, in person. It is a great feature.
And the brick and mortar book stores can carry ebooks of best selling authors (or a newbie author if they want) at no initial cost to them. They make their money when they sell the digital book.
Seriously, http://www.enthrill.com enthrills me.
And no, I am not being paid to talk about them. This is just plain old sharing of great information for budding new authors.
I will let you all know how my first order with them goes for my first book, that I just published. (Correcton: How Vedic astrology predicts the market instability of 2013.)