Here’s a video tutorial on modeling giant science fiction crystals. The intent is making large, emerald style crystals for Necron terrain, but I can see these in any number of settings, including pulp action lost worlds.
modeling
Making Counters For Games
The League of Ordinary Gamers has a tutorial on making counters for your games.
Making Bayou Swamp Terrain
Here’s some good viewing on making Bayou swamp terrain.
Bag End Bonsai How to

It’s not miniature wargaming, but fans of Tolkien and miniatures in general will love this Bag End Bonsai.
Modeling Shrubs
The Mordheim in Montana blog has an illustrated article on making bushes and shrubs for your 25mm wargames.