Many moons ago, TSR / Wizards of the Coast released a series of paper buildings for use in D&D games. They’re now available free for the downloading. Any medieval / fantasy wargamer will find these useful. I think they’ve really stood the test of time.
The Miniature Wargaming Editor
Liberated Hordes – South American Wars of Liberation Rules
Liberated Hordes is a set of free wargames rules for the South American Wars of Liberation. They rules are an amendment to the Hordes of the Things rules (HOTT).
Inquisitor Rules 40k Universe
Inquisitor was game produced by Games Workshop set in the Warhammer 40K Universe. Curiously, it used 54mm figures.
The game is out of print, but a rules archive is at the link.
Building An Inexpensive Game Board
Here’s an instructional video on building an inexpensive game board.
History and Uniforms Military History Magazine
You can get a free copy of the new History and Uniforms military history magazine at their website.