The Complete Wargames Handbook
http://www.hyw.com/Books/WargamesHandbook/Contents.htm
If wargaming has a Dalai Lama, it is James F Dunnigan.  Dunnigan wrote the book on wargaming in most every sense of the word, and this is the book.  Best of all, it is available online. Dunnigan is also editor-in-chief of The Strategy Page, a website of StrategyWorld.com.

Web-Grognards
http://grognard.com/index.html
Web-Grognards is one of the best comprehensive wargaming sites on the web.  It's a site biased toward serious, veteran wargamers.  Grognards hosts an encyclopedic list of wargame reviews, articles, and other information, and provides links to some of the best wargaming sites on the Web.

Consimworld
http://www.consimworld.com/
Slightly more commercial than Grognards, Consimworld's main strength is its vast discussion boards with over 6,000 participants.  Discussions of almost every imaginable topic involving hobby wargames are currently in progress.

Wargamer's Ring
http://www.marinergames.com/webring/wargamer.htm
A 600-plus site web-ring of sites devoted to wargames.  The quality varies, but the general theme doesn't.

BOARD WARGAMES SITES

Open Directory of Board Wargames
http://dmoz.org/Games/Board_Games/Wargames/
The Open Directory is a great concept: volunteers index the web.  This page offers over a hundred links to board wargames sites organized by category.

Cardboard Strategyst
http://homer.pacific.net.sg/~grognard/wargames/
A low-tech, but friendly site with lots of good information about board wargames.

Gamer Cadre
http://home.earthlink.net/~jamiranda/gaming.html
A page operated by Joe Miranda, the editor of Strategy and Tactics magazine.  Mr. Miranda's interest run far beyond board games.  His site provides a nice little description of the Connections 1999 and has a great link list to material on RMA issues.

Waterloo
http://www.cstone.net/~jsetear/games/waterloo/
An example of one of the many enthusiast sites devoted to particular games.

MINIATURES WARGAMES SITES

The Miniatures Page
http://theminiaturespage.com/
This seems to be the leading miniatures site on line, based on link popularity.  The site has tons of information about, what else, lead miniatures.

Major General Tremorden Rederring's Colonial-era Wargames Page
http://zeitcom.com/majgen/
Major General Rederring is the "fictional commander of British army units in the equally fictional subcontinent of Ouargistan, sometime in the latter 19th and/or early 20th Century."  A really fun site with visual appeal, representative of the best of the miniatures club sites online.

COMPUTER WARGAMES SITES

The Wargamer
http://www.wargamer.com/
Computer wargame sites don't get much better than this.  Demos, discussions, previews, and articles on computer wargames--and a snazzy interface to boot.  Very extensive and accessible.

COMBATSIM.COM
http://www.combatsim.com/
A very snazzy computer wargaming site with an emphasis on realistic simulations.  The site offers previews and reviews of games divided into categories of land, air, sea, and space combat.  There are also links to information on real military history and weapons platforms.

The Gamer's Net
http://www.thegamers.net/newswire.asp
A big site full of computer wargames.

Rugged Defense
http://www.xs4all.nl/~cyberfox/
A play by e-mail wargame club.

PHYSICAL WARGAMES SITES

The Online Paintball Network
http://www.onlinepaintball.com/
If your browser is flash-enabled, you can see a snazzy opening sequence to this site, which hosts a fair amount of good paintball information.

Khan Jal's Laser Tag Page
http://www.geocities.com/Area51/Station/5487/lasertag.html
Paintball's chief competitor incorporates a sci-fi twist.  Note the nice "spacey" background on this comprehensive laser tag site.