d20 System

Ancient Worlds: Multicosm
Includes ancient Rome and Iceland campaign settings, new clases, feats, solo adventures, monsters, new rules, and product reviews.
http://www.angelfire.com/rpg2/ancientworlds/

The Boneyard
d20 conversions of creatures and rules from Advanced Dungeons and Dragons and Alternity.
http://www.geocities.com/kanegrundar/

d20 Magazine Rack
A site that has free downloadable electronic magazines such as d20Zine and TempesT's Lore, product reviews, gamer resources, and gaming contests.
http://www.d20zines.com

d20 Modern Roleplaying Game
The official site for The Wizards of The Coast d20 Modern RPG. Features free articles, downloads and artwork for the game.
http://www.wizards.com/default.asp?x=d20modern

d20 Tools
Contains tools for the d20 system such as new equipment, feats, skills, classes, and characters.
http://www.geocities.com/nuelow/d20tools.html

DireKobold.com -- A D20 Adventure E-Zine
An internet D20 adventure magazine dedicated to the three principles of quality, quantity and flexibility.
http://direkobold.com

Fantasy gaming SRD
SRD for d20 roleplaying games in a fantasy setting.
http://srd2.astrally.com/

The Gundam D20 Homepage
This is the homepage of the free D20 role playing game system conversion for Mobile Suit Gundam.
http://www.geocities.com/admarmitage15/

The Hypertext d20 SRD
Contains the version 3.5 d20 system reference document and is indexed, hyperlinked, and searchable.
http://www.d20srd.org

Modernized! - D20 Modern Ezine
A free ezine, published to the web, that provides new material, suggestions, and other useful bits for a D20 modern campaign.
http://www.intrepidheroes.com/modernized.htm

Open Gaming Foundation
Contains Open Gaming Licenses and a clearinghouse for information about the system.
http://www.opengamingfoundation.org/

Palaestra: A Land of Magic and Intrigue
Maps, fictional stories, artwork, house rules, campaigns, and general game information
http://webpages.charter.net/wpeacock/palaestra/

PCGen
A character generator and maintenance program aimed at supporting any and all d20 roleplaying games.
http://pcgen.sourceforge.net/

RolePlayingMaster
A software utility suite for D20/Dungeons and Dragons, incorporating character/NPC/monster generation, adventure building, and in-game combat/BattleMap manager.
http://www.enworld.org/RolePlayingMaster/

RPG Vault
Features new races, feats, and classes for the DC and Everquest universes.
http://www.geocities.com/jugheathius/

RPGAttitude: D20 RPG Site
A website that contains new generator programs for the D20 system such as the NPC and Treasure Generator.
http://www.rpgattitude.com

Ruby Covenant Roleplaying
Australian based web site that offers D and D and d20 roleplaying information and products to RPG fans.
http://www.rubycovenant.com.au

Shadowrun D20 Conversion Site
A conversion site for the Shadowrun system by Wizkids to the D20 Format.
http://www.geocities.com/grinningkat/

Starcon Continuum Homepage
New rules for a futuristic D20 campaign. Has information on starships, new skills, weapons, along with bios of characters in the world.
http://starcon.ionichost.com

SVGames - Global Game Source
Offering d20 games and accessories worldwide. Cheap shipping and thousands of items. Managed by an award-winning team.
http://www.svgames.com

Weird War II - The Complimentary Website
Has variant rules, new equipment and vehicles and information for the PEGInc game Weird War II: Blood on the Rhine (and expansions).
http://www.mchome.net/dirk/weirdwars/

Slashdot: Where Daemons and Dragons Collide
Feature story of the Open Gaming Project with reader feedback. <small>(March 22, 2000)</small>
http://slashdot.org/features/00/03/22/0950237.shtml

Salon Technology: Dungeons & Dragons to go open-source
An interview with a gaming executive about an open gaming license for role-playing games. <small>(March 10, 2000)</small>
http://www.salon.com/tech/log/2000/03/10/dungeons/index.html