Eagles and Emperors is a set of free wargames rules for the Napoleonic period based on a set of Civil War rules called The Blue, The Grey and the Butternut.
Rules: Napoleonics
Bring Out The Old Guard Napoleonic Rules
Bring Out The Old Guard and That Vertically Challenged Mediterranean Man is a set of free wargames rules for the Napoleonic period.
eRules Napoleonics
eRules is a set of free wargames rules for the Napoleonic era. From the introduction:
eRules Napoleonic.txt is a set of rules for the Napoleonic wars designed by WargameSystems following the same principles as eRules World War II, except that Napoleonic.txt is provided free as a draft document for you to download, try out and contribute to. Let us have your suggestions for adding to it or improving it.
Eight Bells Napoleonic Paper and iPhone Rules
I wonder why this hasn’t been done before. Eight Bells is a set of paper rules, combined with an iPhone app for playing Napoleonic naval games.
Gettysburg Gamers’ Napoleonic Rules
Gettysburg Gamers offer a set of free wargames rules for Napoleonic warfare.