The Germans don't do cards, and you would certainly not give a card to someone you are going to see anyway. Having said that, I have a list of 50-60 people in various countries that I post cards to.
Like pollyperkins, I send a round robin and like to receive those from my old school friends telling me their family's news. I have never seen one which boasts of children's achievements - I think that is an invention of columnists and comedians.
When the children were small, I would make all our cards, and then we would all sit round the table and everyone signed the cards, and we were like a little conveyor belt, putting them in the envelopes, sticking them down and stamping them.
I have since learned that they hated that chore!
Since the children got older, I have also bought cards with no words inside, which I put through the printer with a personal seasonal greeting and a short newsletter (I love mail merge), and, especially, with our address and phone number and e-mail addresses clearly printed, which has often meant that I get a reply where I may not have heard from them that year.
My mother tried e-mailing one year, but she said it didn't feel right, so she's reverted to proper cards. I am going over next week to visit her and, as I often visit her in November, when it's her birthday, I shall buy a sheet of stamps for her to send her cards. She is able to do the addresses on the computer, but nowadays she addresses them by hand in her sturdy copperplate handwriting which does her proud at 97!