Today, March 31 you can send a free card from your iPhone or Android device through a Sincerely partner app. Just download one of the apps located here and here. Add the picture you’d like to use and log in or register. By downloading the app you should have earned enough credits to send the card for free.
From Sincerely’s Facebook page: Sincerely Inc was founded in 2011 with the mission of making it easy to send a printed photo, the world’s most ubiquitous gift, from your phone.