Warhammer Napoleonics is a set of stat lines and modifications for using the basic Warhammer Rules for the Napoleonic period.
In 1858, a group of surviving soldiers of Napoleon’s Grand Armee were photographed wearing their original uniforms. You can see the photos at the link.
Captains Bold is a free print-and-play game for the age of sail. It focuses on duels between frigates.
Bugle and Shako are a set of free wargames rules for quick playing Napoleonic askirmish games.
Land of the Lead has a set of one-page Napoleonics Rules. They’re designed for play with a “reinforced division” per side. Scroll down to the bottom of the page to find them.