Once you have your chi card, which you can subscribe to here: http://www.chi-card.com/activate.html
you, of course, know that you can print the card out and carry it in your wallet.
What you may not realize is that printing the card out isnt even necessary. You can also use it as a background image on your iPhone ... The image above is my background on an iPhone 4s and I'm going to detail the steps to add yours as a background.
First you'll receive a jpg file