Mantic offers its Dungeon Saga fantasy rules free for the downloading.
Miniatures Rules
Warpath Rules
Mantic offers its Warpath science fiction rules free for the downloading.
France 1940 Map and Counters
John Cooper has made some graphical improvements for the classic Avalon Hill game France 1940 and made the maps and counters available as a download. I remember having a lot of fun playing the game, and this artwork is a great visual improvement.
Elder Scrolls Miniatures Game Rules
Modiphius is offering a free PDF of their Elder Scrolls Miniatures game.
Peep Wars Wargames Rules For Marshmallow Candies
What do you do with all of those leftover Easter candies like marshmallow peeps and jelly beans? Play a wargame, of course. Invisible City Productions has rules for just such a scenario, called Peep War