Lands of Mystery
Dungeon Magazine had an ongoing feature called “Maps of Mystery” which featured small maps, not tied to a specific adventure. These maps were useful to me for side trecks and pregenerated dungeons. The final issue of Dungeon came with a poster map titled “Lands of Mystery”.
This map details a whole setting, reaching from the Frostmere in the north to the Rainlands in the south. The individual maps from 31 issues of Dungeon are highlighted as locations on the poster map. Besides these maps and evocative names, there is no backstory or history for the setting, presenting a blank slate for a campaign.
Although I have some ideas for specific locations, the majority of the map is open to interpretation. This allows for a lot of freedom is fleshing out backstories for the PCs.