One app that I've loved this summer is Marco Polo. My wife joined it in the spring to chat with a few of her friends. I initially resisted, but I finally relented, and I love it. I used it all summer with my wife and some of our friends.

Yes, you can do this with iMessage, but Marco Polo makes it easier. You can also have group chats and add funny filters. I've found it a great in-between from phone calls (that can be invasive) vs iMessage (sometimes the meaning doesn't come across right). It's almost like a private SnapChat.

You can download Marco Polo on the App Store for free.