Rules We Use:

Red Coats and Hunting Shirts: Paul Silberman's American Revolutionary War rules. These are a variant of the Greenjacket Rules.

Tanzanica: Darkest Africa Skirmish rules based on Games Workshop's Mordheim rules. By Brett Abbott.

Sword and the Flame (and Sword in Africa): Larry Brom's classic Colonial game. 20 Years old and still the most played set of Colonial rules.

Crossfire: Infantry based WWII rules that use a momentem based turn sequence. We use these for both WWII and Spanish Civil War.

Warhammer: Games Workshop's Fantasy Battle rules. Expensive but very nice figures and a very rich background.

Johnny Reb: Grand Tactical American Civil War rules by John Hill. A really good period feel make these rules stand out from the rest.

Two Page Skirmish Rules: Simple Skirmish rules for simple people from the Colonial Angle web site.