Amazon is offering a FREE $5 credit when when you make a qualifying app or game purchase via this link! The apps are priced at $2.99, so you will basically be getting a free $2 credit to your account.
Once the app is purchased, you will receive an email and the $5 credit will automatically be applied to your account.
Note: It seems that you don’t actually need to download the app to receive the credit. All you need to do is opt to download. If you are not an android user, it will give you a warning that the download may not be compatible with your device, just ignore it, as you do not need to download anything. If you are using an i-phone, you may need to select “full site” on Amazon’s mobile site to get this offer.