The Miniature Wargaming Editor The Charge! blog has an article on making cheap trees for your gaming table out of roofing nails and old sponges or foam.
A guy in our gaming group did this many years ago. Tragically, at one point, he leaned over the table, lost his balance and put his hand down to catch himself. His hand landed on one of his own trees, and drove the nail through his palm.
That avenue for cheap trees was a dead end, as far as the rest of us were concerned.
Here’s a very nice online program for generating hex sheets for use with wargames and role playing games. I just used it to generate the paper for a hex based wargame.
Hunters on the Shoreline is a set of free wargames rules for playing WWII coastal naval actions using 1/600 miniatures. It’s available from PT Dockyards.
Here’s a photo tutorial on making a terrain cloth. A well done cloth can really add something to your games.
The Combat Storm site has a couple of modern middle eastern buildings available for downloading. They’re scaled for those green plastic army men, so you may need to resize them on printing if you want to use them with smaller scales.