Away Boarders is a neat little game for a little-considered theatre of war: The Great Lakes in the late 18th and early 19th centuries. The author also includes some nice 2-D paper models of the ships, as well as counters.
naval
Firepower Naval Rules
Firepower is a set of free wargames rules for naval battles. The rules cover the period 1900 – 1945.
A Hotter Fire ACW Naval Rules
A Hotter Fire is a set of free wargames rules for naval combat between civil war ironclads.
Der Tag Naval Rules
Der Tag is a set of free wargames rules for WWI naval warfare in 1/6000 scale.
Ram or Die – Battle of Salamis Rules
Ram or Die is a set of free wargames rules (and paper figures!) for refighting the Battle of Salamis.