NSTA-MEMENTO Vacation’s almost over, and you’ve forgotten to buy that postcard Mom’s expecting. (Why she doesn’t just follow you on Instagram, you’ll never know.) Enter Postagram, a mobile app that creates a physical postcard from the photos in your feed. You could be boarding the plane and still have a few minutes to choose a photo, customize the card background, and ship it for $2. Or do one better and snap a selfie in front of that iconic landmark—that’ll really make Mom’s day.