I learned a while ago that when visiting another city it's easy to get lost. When I have one of these in my pocket, I have a point of reference. This comes in handy when trying to get back to my room, in remembering names of my hosts, and as a referral when I'm home.
A few years ago, we took our 17 year old daughter on a three week, four country, European trip. Every other day we were in a new place. As we checked in, I would have my daughter pass on the candy dish and grab the little card with the name of the place we were staying. That way, should she become separated from us, she could show a local the card and get back without wondering all over, perhaps, Venice.
In return, when checking out, we'll leave a hand written Thank You on our hometown postcard. Now, with this little business card tucked into my journal, not only will I know my hosts name but the correct spelling.
Once, after a wonderful stay in Westport Ireland and hiking Crough Patrick, I would curse St. Patrick as I clambered up and down the stairs of our B&B with my sore muscles. It wasn't until later that I learned our hosts' Gaelic name, Padraig, also meant Patrick. So on my addressed postcard, I went with Padraig. Interestingly, Padraig was not of Irish descent but Asian Indian.