The Wargames Table blog has a good idea for filling in the blank spots on a movement tray.
Modeling
Making Jungle Trees
The Wargame Terrain Blog has a photo tutorial on making jungle terrain.
Making Haunted Woods Bases For Your Miniatures
Here’s a tutorial on making a Haunted Woods base for your miniatures. THe video is aimed at a single base for a miniature, but I think the techniques could be extrapolated to more general base terrain.
Modeling Swamp Trees / Cypress
Here’s a video on modeling cypress trees / swamp trees.