Here's a diorama I made for a competiton earlier, with some customized steampunk miniatures & scratchbuilt terrain.
The medieval buildings you'll see below have seen a lot of use in my rpg's. I love running games in cities, so it's no wonder - and the campaign I'm just about to finish is Ptolus, a huge book having a complete urban setting for D&D 3E.
The buildings are built almost completely from cardboard + surface materials - that's same old filler powder/PVA glue mixture I've used in so many of my models.
Most frequent question I get asked on gaming sites is about how I have created fire and smoke. Now I'm releasing a tutoral about this topic - while it's actually about creating starship wrecks, it will teach you how to model fire. Another page (coming soon) will show you applications of this technique.