Professional Organizations
International Game Developers Association - http://www.igda.org
IGDA Austin Chapter - http://www.igda.org/austin/
Conferences and Expos
Game Developers Conference (San Francisco) - http://www.gdconf.com/
Austin Game Developers Conferences - http://www.austingdc.net/
South by Southwest (SXSW) Interactive - http://sxsw.com/
Independent Game Conference - http://www.independentgameconference.com/
E for All - http://www.eforallexpo.com/
Electronic Entertainment Expo (E3) - http://www.e3expo.com/
Penny Arcade Expo - http://www.pennyarcadeexpo.com/
Game Development Engines
Source - http://source.valvesoftware.com/
Unreal - http://www.unrealtechnology.com/technology.php
Torque - http://www.garagegames.com/products
XNA - http://creators.xna.com/en-US/
GameSalad (Created by EGaDS founder, Michael Agustin) - http://www.gamesalad.com
Aurora Neverwinter Toolset - http://nwn.bioware.com/builders/
Half-Life Modding/Mapping
The Whole Half-Life - http://www.twhl.co.za/index.php
Inerlopers.Net - http://www.interlopers.net/
Useful Websites
Gamasutra (Job boards and developement forums) - http://www.gamasutra.com/
Gamedevmap (Global map of company locations) - http://gamedevmap.com/