Drake: The Dragon Wargame is a set of free wargames rules for fantasy wargames focusing on Dragon leaders with their servants and lieutenants.
Rules: Fantasy
Panzerfäuste Unarmoured Fantasy Rules
Panzerfäuste Unarmoured is a set of free wargames rules from Wessex Games. The free edition is a stripped down version of Panzerfäuste, Wessex Games rules for fantasy World War II.
SAGA Isengard Battleboard
A Saga battleboard and army list for the forces of Isengard from the Lord of the Rings.
Two Page Lego Minifigs Rules Set
Consortium Games offers Minifigz, a two page rules set for battles with Lego minifigs, and similar mini people. I’m going to have to give this a try.
Update: The original link is dead. You can still find Minifigz on the Wayback Machine.
Dungeon Saga Free Rules
Mantic offers free rules for their Dungeon Saga game.