Flag is a recent Kickstarter campaign for a free photo-printing service. Yes, you read that correctly. The entire service—printing, shipping, and all—is completely free, at least for people in the U.S. It sounds crazy, but the way they plan to accomplish this is by putting an advertisement on the back of each photo print.

I'm generally not a fan of obtrusive advertising, but if you're going to frame or hang your photo prints, then you most likely won't even see these ads most of the time anyway. They also plan on offering ad-free prints for a small fee.

The photos will be ordered via an iOS app, with various sizes and border styles available to choose from. It will even be possible to divide a huge photo into individual prints that can be assembled jigsaw-style into a poster upon delivery.

Whether or not you think you'd ever use Flag, you should at least watch the funny promo video, guest-starring Adam Lisagor.