Space Fleet 2014 is a set of free wargames rules for fleet actions. It can be played on a hex grid or open tabletop, and there are rules for ship design, campaigns, sensors, and more.
Kings of War Variant: Romes’ Rise and Fall
Kings of War is a great fantasy rules set from Mantic Games. Here’s a variant for Rome’s Rise and Fall.
Unofficial Warhammer Fantasy Halfling Armies Book
Here’s an extremely well done unofficial army book for halflings in Warhammer Fantasy.
Trierach Classical Naval Warfare Rules
Trierarch is a set of free wargames rules for naval warfare in the classical era. The game is based on DBA, with measurements expressed as “ship lengths.”
Island Mayhem Rules
Island Mayhem are a set of free wargames rules for pirates.