The Solitary Wargamer offers a variant of DBA for the English Civil War.
Home Fires ECW Campaign Rules and Map
The Solitary Wargamer offers a set of free English Civil War campaign rules called Home Fires.
Internet Medieval Sourcebook
The Internet Medieval Sourcebook is a fantastic resource for miniature wargamers. I’ve had this one in my bookmarks for several years and haven’t even begun to plumb its depths. The section on the Crusades is particularly useful.
MG-42 Two Hour Wargames Introduction
MG-42 is a set of free wargames rules designed as an introduction to Two Hour Wargames’ Reaction system.
Slammer Skirmish Science Fiction Rules
Slammer Skirmish is a set of free wargames rules for science fiction skirmishes. The author writes:
Slammer is a set of wargame rules for Science Fiction skirmish games using miniatures. Slammer is not tied to any specific background or company product line, you can use whatever figures or models you have. I intended from the start that Slammer would be flexible and adaptable to different scenarios. I have intentionally kept it fairly ‘loose’, particularly in areas like troop motivation and Hollywood heroics. Slammer is meant to be fun!