Calling Cards

Do any of you use calling cards? Now with iPhones making email and finding contact information so easy.. I'm guessing not many people do. My mom however has been asking for me to design and make her some for a good year or two now. I finally made some for her birthday this year :) I imagine they could be good for when you take a meal to someone, you can leave your card in the bag to make returning the dishes easier. Or perhaps leaving your card in a book you loan to someone in case they forget who they borrowed it from. And of course, passing someone a pretty calling card is such a warmer and more personal way of saying "call me anytime" than forwarding your digits via text. Anyways, I suppose if not many people use calling cards anymore.. there are still a good number who keep business cards on hand. Let me know what you think! Would these be something you'd like to see for sale in my etsy shop?