Apple has released their new Cards app which allows you to create physical cards personalized with your photos and text and mail them right from your phone.
I just tried it out, and within minutes, I created a card with my daughter's photo, added my own text, and ordered it to be shipped to my mom. I would like to see more card templates in the future, including some that are "just because". However, you can change the text to any of the templates and make it your own.
When I first learned about cards, I was indifferent about it because I didn't expect to use it much because I'm not the type of person who sends other people cards. However, now that sending a cards is so easy, and so personal, and so affordable. I think I'm going to start sending out more cards.