Remember postcards? Postagram brings back the old snail-mail staple, but with a high-tech twist. Take a photo with your smartphone camera (or choose one from your Instagram or Facebook account), type in a short message and enter the recipients’ address. A personalized postcard will appear in their (actual) mailbox within a few days. For iOS and Android; app is free, postcards 99 cents each for U.S. delivery, $1.99 for international addresses.