I am a huge fan of postcards, both to receive and to send, and especially if they are sent from an unusual destination with a stamp from that destination.
Sometimes, I may be back home and sharing pictures before the postcards arrive, but everyone who receives the postcards still seems to enjoy them.

Once, a friend receive my postcard from Mexico a month after it was sent; he was completely baffled as neither the date I wrote on the card nor the postmark were easily distinguishable.

I wish more people would send postcards (and old-fashioned letters too).