CHARACTER SHEETS

NBarbarian Character Sheet - WotC's official sheet for the barbarian class.
NCharacter Trait Sheet - Contains tables with over 400 personalities, over 150 quirks, plus tables for speech, hair, and facial characteristics.
NCrusaders of the Net Files - Includes an extensive "Character Workbook" for those of you with OCD, as well as a Living Greyhawk character log.
NEma's Character Sheets - A wide variety of character sheets here.
NLevel Progression Sheets - Sheets for all eleven core classes.  Use these to plan your character's advancement.
NLiving Greyhawk Download Files - Living Greyhawk character sheets and whatnot.
NLiving Greyhawk Master Item Log Sheet - Keep track of all your gear.
NMad Irishman Character Sheets - Includes both the Living Greyhawk character sheet and a great 3E Adventure Record sheet.
NMagic Reference Sheet - Tables and information for spells and magic, magic-related skills, familiars, psionics, and information on magic items.
NOriental Adventures Character Sheet  - WotC's official sheet for Oriental Adventures!
NPlayer Reference Sheet - Contains a summary of actions you can take during combat, a list of combat modifiers, and tables for skill checks.
NRPG Sheets - Lots of different character sheets for several systems and editions.


DM REFERENCE SHEETS

NCampaign Reference Sheet - NPC information, PC class summary and monster advancement charts, as well as XP and treasure charts
NDungeon Master's Adventure Log - A great "cheat-sheet" to help speed play.
NDungeon Master's Reference Sheet - Contains a summary of various conditions, charts for doors and walls, spotting, weapons, etc.
NRPGA Initiative Cards - For use in speeding combat.


MAPS

NWotC's Map-A-Week Archive - Lots of generic maps, villages, temples, taverns, towns, castles, dungeons, caves, graveyards, cities, etc!


MODELS, COUNTERS, & TOKENS

NWotC's Fold-up Paper Model Archive - Choose from a variety of different DIY structures, including cottages, a bridge, city walls, and more!


RULE INFORMATION

NGame Rule FAQ - Look here first for answers to your rules questions.
NOfficial Errata - Corrections & clarifications for various rulebooks.
NSystem Reference Document - The basic 3E d20 rules.