[CelestialGoblyn]

This is a *great* idea.
Now, I'd need to research for details, but just a few ideas:

Innsmouth with cultists and fishmen.
Shaolin with disciples and monks.
Village defended by seven samurai.
Cimmeria, land of barbarians, with Conan as one of them.
Kirke's island from Odyssey, sorceress and a horde of beasts and foulspawn.
Holy sanctuary with clerics, flagellants and paladins.
Transylvania with a vampire count leading an army of infartry, peasants, villans and wolves.
Highlands with banshee's and barbarian swordsmen.

For underwater:
Land of the drowned - full of undead.
Sunken city - mechanical men, golems and other animates.
Lair of the kraken - pretender-sized octopus with items