Amazon is running a new promotion that will earn you a $5 Amazon credit for downloading a select free Amazon Underground app. Unfortunately, the promotion is only for first time Amazon Underground downloaders, so most of you probably won’t qualify. For those of you who have never downloaded an app through Amazon Underground, earn your free $5 Amazon credit by downloading either Simple Sudoku, Simple Solitaire, Flow Free, Fruit Ninja Academy, Elmo Loves 123s, or My Boo. This promotion ends May 8. The $5 credit you earn will automatically be applied to your next purchase on Amazon.