The League of Ordinary Gamers has a tutorial on making counters for your games.
modeling
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.
Making Expanding Foam Hills and Rock Clusters
Here’s a nice tutorial on making cheap and easy expanding foam hills for your wargames table.