The 18 Charlie site has a nice photo tutorial on making bocage for your 15mm wargames.
The Miniature Wargaming Editor
15mm Palm Tree Tutorial
18 Charlie has a tutorial on making 15mm palm trees. The methods looks good, and should be quick and inexpensive.
Napoleonic Wargames Rules
Paul Leniston offers a set of free wargames rules for Napoleonics. He and his gamer wife have been playing and testing them for many years.
World War III Rules
World War III is a set of free wargames rules for the period “1950 to armageddon.”
One Page Kill Team
One Page Kill Team is a set of free wargames rules for small scale skirmishes in the 40K universe.