Ryan Scow has a tutorial on making miniature wargames trees from sage brush. They are very good looking.
Ryan Scow has a tutorial on how to make balsa strips look like timbers for use in models of half timbered houses, stairs and other miniature wargames terrain projects.
GHQ, maker of those fabulous microscale armor and ships has a tutorial on making ocean hex tiles. The techniques also could be applied to other terain forms, such as those large styrofoam squares so many seem to use.
WarFactory has a tutorial on making African Acacia Trees.
Steve Jackson’s Ogre is a classic game. I first got a copy when it was in a small bag with thin cardboard cutout counters. It’s gone through several incarnations since then, but the idea of hordes of GEVs and infantry against a single cybernetic tank. Now Dan Efran has a page describing how to build Ogre pieces with Lego. Its really cool, and I can’t wait until my kids outgrow the things and I inherit them.