Greetings From...is the latest craze in the Postcrossing community. It is a series of postcards representing an image and data about the country in question. They are issued by one online shop, which I have contacted a while ago asking if Croatia is in the production line, but I guess so many people want an issue of their own country it may take a while to get a response.
I have no intention to make a GF collection, but I have swapped for a few to have examples. Two I have received, South Korea seems to be lost or perhaps never sent.