The Old School Encounters Reference, labeled as CDD #4 on Kellri's blog, is crammed full of various tables, including an expansion of the random wilderness system from the 1e DMG. Because the basic terrain generation procedure is identical to the DMG procedure, I won't generate a new map sample, but I'll talk about the expanded portion. Note, though, that the DMG specifies rolling for hexes of any size from 1 mile up, while Kellri's procedure limits this to the 25-mile hex scale.
The key addition is a couple pages after the terrain tables. There's an encounter table keyed to different terrain types, but "encounter" here means more than just "monster", but also includes weather changes, structures like fortresses and ruins, settlements, and disasters. Similarly, the sea encounters table includes creatures, events, land, and finds like shipwrecks. The inclusion of wandering monster encounters means the table is definitely intended for stocking hexes during play, but the presence of settlements and structures means that the table is also creating the world.
Additionally, there are other tables to flesh out many of the entries on the land and sea encounter tables; path and road descriptions, castles, and an entire section on features in settlements.
Pros: Adds some missing details to DMG wilderness system. Takes into account on-the-fly needs.
Cons: Terrain features are still pretty broad. Settlements may be too rare. Including large settlements on the random encounter tables means that, potentially, a town or city may appear in a hex the second or third time you visit it. Lots of tables slows down the process.