With the new Fog of War feature for Hardcore servers, it would be cool if a player could craft the "Paper Map", which is already in Rust and then they could go to another player that also has the Paper Map, press a key or use a command and the two player's maps combine. Since the Fog of War is new, and still on Staging, I'm not sure if there's even a way for the map to be expanded without the player exploring it themselves, but this would be cool.