You may recall that before the Wii U launched Nintendo shared information about a Digital Deluxe Promotion. This was announced as a bonus for those who pick up the more expensive of the Wii U systems. Deluxe owners would then be rewarded with points on every digital purchase they make with the system. Although it didn't go live at launch, a few weeks later it is now available.
In order to use it, you must log in with your Nintendo Network ID and password and from there can begin getting points back for digital purchases you make on the system. However, the purchases must be Wii U eShop ones, not 3DS purchases or even Wii Shop Channel items access through the Wii U, so keep that in mind.
Users will get 10% of an eShop game's value back in points. For example, if you were to buy a $59 game digitally, you would get 599 coins back. Regardless of what you buy, once you get to 500 points they can be exchanged for $5 of eShop credit. This promotion won't last forever, but you have a while, as points can be received from purchases all the way until December 2014.