Mint Works is an acclaimed worker placement game that’s designed to be stored in a mint tin (thus the name.) While sold commercially, you can get a print and play version for free.
Postcard Cthulhu is a print-and-play cooperative worker placement game set in HP Lovecraft’s Cthulhu universe. The game quite cleverly is designed (as its name suggests) to fit on both sides of a postcard. In deference to my older eyes, however, I printed it on a full sheet of paper. The postcard version, however, would travel well.