Bob Bergman has written Ironsides, a set of free wargames rules for 6mm English Civil War. A this point, they consist only of a turn sequence, and the necessary charts.
Martin Soilleux-Cardwell has these instructions on building a 15mm redoubt. He built his for a Fontenoy scenario, but they would work for any number of 17th and 18th century miniature wargames.
For the serious wargamer, Osprey books can get expensive. But for many periods they are the only source of miniature painting guides. For the American War of Independence, you have an alternative. This site has a fabulous collection of color plates of American Revolution uniforms.
Devil Dog Design has a free download of its Dogs of War rules. These wargames rules go with their 25mm figures for miniature wargames of recent conflicts in Afghanistan, Somalia and Iraq. They are on the more detailed side of things, requiring players to keep track of ammunition and such.
The Wargames Journal has Age of Blood, a set of free campaign and skirmish wargames rules for Vikings. What I like about these is that they contain elements of the fantastic: your warband can fight against trolls and giants. There also is a "Fate Deck" mechanism that should add a lot of flavor to your games.
I have got to start painting Vikings!
Here's an article from Arofan Gregory on an "environment", rather than "actor" approach to turn sequencing in wargames rules. It's worth thinking about.
Miniature Wargaming is part of the "adventure games" hobby, which includes r ole p laying and board games. Wargamers recreate battles on the tabletop with toy soldiers, like a more complicated game of chess. Models range in height from 6mm to 28mm tall, with 15mm and 25mm being the most popular. There also is a growing interest in toy soldiers and military models, such as the 1/32 and 1/35 scale plastic soldiers from Conte, and Marx.
The most popular miniature wargames are fantasy and science fiction based, such as Warhammer, Warhammer 40K, Warmachine and The Lord of the Rings. World War II games such as Flames of War and Axis and Allies are new favorites. Other favorite historical periods include Napoleonics, the American Civil War, and ancients, such as Romans or Greeks. Other gamers enjoy miniature naval wargames, recreating battles like Trafalgar, Jutland and the Coral Sea.
Hobbyists research historical periods and paint their tiny soldiers in accurate uniforms. Others develop "historically realistic" rules sets or build scale battlefield terrain using model railroad techniques.
For pictures, visit the gallery.
Some of the bigger hobby companies are Games Workshop, which produces Warhammer, Wargames Foundry and Old Glory Miniatures. Wizards of the Coast produces several lines of pre-painted miniatures games, such as the Star Wars and Dungeons and Dragons miniatures games, and a historical game with pre-painted miniatures: The new Axis and Allies game. Wizkids produces a fantasy collectable miniatures game, such as the Mage Knight and Heroclick fantasy games, the science fiction games MechWarrior and Rocketmen, as well as the quasi-historical Pirates of the Spanish Main.