Right now, you can get a free $5 gift card for Amazon. How? Download either the IOS (for ipad or iphone) or Android Amazon shopping app and log in with your account for the first time. Sadly, if you've logged in before, you don't qualify--but there is not technically a rule against having two Amazon accounts, if you were to, say, make a new one!

More info available here.

Offer good until June 21st.

ETA: You can download the app on to a Kindle, not just an Android phone.