Postcards from the edge
general journal junk
-
idealog
At the same time they make for a good way to keep a travelogue, postcards can also be a neat way to keep a diary - whether or not what you write has anything to do with the picture on the other side.
It's an especially good way to keep notes you're going to put into a junk journal too, as they're a ready-made thing to make flip outs with by hinge-taping them from a side so they can be turned over to read.
Of course, you could also send one at random to a loved one with something nice on the back to cheer them up, or send one to yourself from a place you're visiting with the recipe of a local dish on the back.