If you never had a PocketStation, Sony’s PsOne memory card with a LCD screen and controller, you can see what all the fuss is about. There is a PocketStation app for PlayStation Vita on Japan’s PlayStation Store. This was originally offered to PlayStation Plus members first, but now everyone can download it.
PocketStation is a freebie too, but you need compatible PsOne classics from Japan’s Game Archive section like Hot Shots Golf 2, Legend of Dragoon, or any of the Mega Man PsOne ports to use it. Final Fantasy VIII has PocketStation support so you can finally play through the Chocobo World RPG and level up Boku.