Fantastic Factories is a free print-and-play dice worker placement engine building game.
Board Games
Midnight Banshee’s Downloadable Boardgame
Ok. So its not really miniatures related, but it’s still really neat. Ravensblight has a downloadable game called Midnight’s Banshee which is a cross between a board game and a foldable paper model. The goal of the game is to collect five skulls from the tombs in the graveyard. But be careful, for you never know which one contains a vampire. There’s a clever spinner under the game board which randomizes the locations of the vampires.
Methuselah Vampire Hunting Game
Warpspawn games has a vampire hunting game called Methuselah designed to be played on a chessboard with a custom set of cards. One side plays Dracula and his minions, the other the vampire hunter and his assistants.
I think that some of the ideas could easily be lifted for use in more traditional miniatures games.
Downloadable Terrain Tiles
John Cooper has sets of downloadable hexes for making your own wargames maps.
Stalingrad Attacked
Lou Coatney offers Stalingrad Attacked, a free, complete board wargame. Coatney is a veteran game designer with a number of published designs, including Dark Crusade.