Nintendo has announced a Wii U promotion in North America where you can earn up to $10 in eShop credit by adding funds to your store wallet. It works like this: add $50 in credit and you will receive $5 in credit; add $100 to your wallet and get $10 in extra credit. To be eligible for the additional funds you will need to act before the clock strikes midnight PDT on July 28. The extra credit will be added by August 2. More through Nintendo. Thanks, Joystiq.