Italian wargames magazine Dadi&Piombo (Dice and Lead) is offering a free set of modern skirmish wargames rules called Breaking News
In the Noonday Sun is a set of rules for small unit actions, derived from another set called Slammer. The authors of Noonday write:
In the Noonday Sun is a set of wargame rules for skirmish games using miniatures. I intended from the start that Noonday Sun would be flexible and adaptable to different scenarios. I have intentionally kept it ‘loose’, particularly in areas like troop motivation and Hollywood heroics. Noonday Sun is meant to be fun! We use miniatures on the tabletop to represent men and women who might well be scared or heroic, angry or bored, professional or just hungry, above all they are unpredictable. When you play Noonday Sun, occasionally try to see things through your troops’ eyes. They are more than just disposable weapons delivery systems.
Blades of Bronze is a set of free wargames rules designed for short skirmish 15mm ancient wargames. The rules revolve around the ability of the leaders to give orders to the troops.
Fast’n’Furious is a set of fast play ancient and medieval skirmish rules. The author writes:
FAST’n’FURIOUS! Is a set of 1:1 simple, fast and fun rules for ancient and medieval skirmish scale games using 25-28mm or 1/72 plastic figures, and designed to cover roughly from 3000 BC to 1400 AD. As well as classic field battles these rules also allow for opposed landing actions and ancient siege operations, as even in ancient times many actions included landings and were directed to assault a fortified site! The emphasis is on fast, simple and enjoyable basic mechanics, suitable for games with many players, but which produce accurate results in harmony with actual historical tactics.
John Armatys offers a set of free modern skirmish wargames rules called Fireteam II They’re designed for use with 20mm figures.