The folks over at Sincerely have come up with a new app for the iPhone based on the Instagram API. In case you don’t know what Instagram is, it’s a photo-sharing service that allows users to easily upload their photos from their iPhones online to share with their friends and social networks online. It comes with a bunch of filters to turn things artsy as well. Postagram takes advantage of the photographs uploaded with Instagram and allows users to send real physical postcards through the app. All they have to do is log in with their Instagram account, select a photo they want to use, add a caption (up to 140 characters) and add an address they would like to send the postcard to. After charging the user’s credit card 99c, Postagram will print out the card and mail the physical card to the entered address. It’s that simple. The postcards themselves are pretty cute, with the ability to pop out the photos on the card so people can just keep the photo if they don’t want the excess borders. Download Postagram from the Apple App Store for free.