Here’s a video of a three divisions of a Napoleonic British Army done in 1:1 scale. Amazing.
Gettysburg Gamers offer a set of free wargames rules for Napoleonic warfare.
Battlelore Napoleonics are a set of adaptations of the Battlelore Fantasy/Medieval card driven miniatures/board game. I like the Battlelore system a lot.
Beware: this site has an obnoxious pop-up video ad embedded in it.
Muskets and Marshals is a set of free wargmes rules for the Napoleonic era. The author writes:
Following the Battle of the Crossroads I have had a final tweak of my house rules Muskets & Marshals. I say ‘final’ tweak even though experience has shown me that there is actually no such thing because tinkering with rules is as much a symptom of my borderline OCD as the desire to keep re-basing my model soldiers is.
That said I am pretty happy with the rule set as they stand and I certainly had a lot of fun playing the game using them. The firing system involves throwing a lot of dice and I’ve found over the years that this always tends to make a wargame more fun than the slide rule/logarithm approach.
The rules are an amalgamation of various rule systems and ideas nicked or created over the last 40 odd years. The movement rates and ranges are straight out of the London Wargames Section Napoleonic Rules (1968). The melee system is spookily like the one from the board game Risk. Many of the other ideas were developed for a set of ACW rules my brother and myself knocked up in the 1980s. The emphasis is on fun and speed of play.
The Lord of the Rings Rules variants Yahoo Group has a set for Napoleonics.