The Battle for Henry Hill is a simulation of the First Battle of Bull Run designed by Matt Fritz for his students. The rules include an order of battle and links to paper figures.
Matt Unsworth offers a set of free wargames rules called The Few that he uses with his students to simulate the Battle of Britain.
Pete Pellegrino offers a set of rules called Sink The Bismark! Pete writes:
Sink the Bismarck! is based upon the Battle of the Denmark Straits, May 1941. The game is designed to be played by a team or 'Flag Staff' determining the actions of each ship in their force. The Flag Staff can consist of any number of players; though recommend not more than 8 - 10 per staff. The staff must have one Admiral in charge of the staff and acting as commander of one ship, and a Flag Captain, commanding the second ship. The remainder of the staff is divided among three departments; the Navigation Department (NAV DEPT) responsible for ship movements, the Engineering Department (ENG DEPT) responsible for battle damage repairs and generating smoke screens, and the Operations Department (OPS DEPT) responsible for guns, torpedoes, and air operations. Each department executes its duties through the use of 'action cards' which they hold.
The rules also include downloads for paper ships, status sheets and card decks.
Matt Fritz offers a set of fast play miniatures rules for World War II Aerial Combat.
The Barons of Fyn is a free downloadable card and tile game from Bones Games. In the game, rival barons try to expand their borders, building a fiefdom of loyal towns and cities, and strengthening their armies. It's beer and pretzels for 2 to 6 players. I've played this, and its fun.