The problem with play by mail games and campaigns has always been verifying dice rolls. You had to trust the person you were playing with to correctly report the result, or rely on a neutral solution, like stock market numbers. This site has a clever solution: it generates numbers and then emails the results to your opponent.
The Alternative History Wars Yahoo group "is meant for alternative history gamers. We deal with wargaming paths not taken during various battles in history. This means it can be related to fantasy or actual historical armies that have never met in the real world. This group is more likely to revolve around the late 1800's to WW1, but it is open to any time period."
The Eyewitness To History site has hundreds of first-hand accounts of major events in history. There is a lot here for games creating wargames scenarios. For example, here is an eyewitness account of the Battle Of Antietam, from David Thompson, a member of the 9th NY Volunteers.
I'm currently painting up some Foundry 7th Cavalry and Plains Indians figures and went in search of pictures of painted figures to use as a model. The Coupstick and Lance Yahoo group was one source suggested to me. The group focuses on Plains Indian warfare and culture from 1790 to 1890. The group also hosts Tim Greene's "Coupstick and Lance" rule set for Plains Indians wars.
Here's are some instructions on building a trench system for miniature wargames set in World War I. I also think that they would be useful for the Warzone science fiction game, which has a definite WWI flavor. This period has experienced somewhat of a renaissance lately, with several companies, including Renegade and Brigade games releasing 25mm - 28mm wargames figures.
Christopher TenWolde has created 10mm World, a photo catalog of 10mm figures. 10mm seems to be a rising standard in the wargaming miniatures world. Old Glory has released a line of 10mm figures, and Games Workshop's Warmaster also is in the scale.
Mandarin's Corner is "Milton's Blog on his hobbies: Miniature gaming, painting, boardgaming in all its various guises (consim, German games), card gaming (MtG), reading (history and Sci-fi), Music (most genre under the sun), and then some..."
Andy Watkins has this page with an amazing list of his ratings on hundreds of historical reference books. It's worth checking before you take the plunge on a particular volume.
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.