Join the Media Insiders Panel and earn a $5 gift card for each device (up to 3 devices) for running the app on your smartphone! It's an easy way to earn up to $15 in gift cards EACH MONTH while you run the device on the background of your phone.
I personally use this and receive my Tango cards every month! You can use Tango cards to get a $5 gift card from the retailer of your choice. I like Amazon :)