Lava seems to be a popular terrain base style — perhaps the whole Mt. Doom thing is stuck in people’s minds. Here’s a tutorial that bills itself as explaining how to make lava splashes, but also has a great deal of information on how to simulate lava in general.
Darkest Africa In The 16th Century
If you’ve got Darkest Africa natives and critters, you can expand your gaming horizons by extending the adventurers back to the 16th Century. Here’s an account of an Englishman in Africa in the late 16th Century.
Making Sub Roman Houses
Here’s a post on making “sub roman” houses — the style of dwelling, however, probably covers five hundred or more years.
Making Rubble Terrain
Here’s an easy way to make rubble terrain with good looking results.