Opposing Force

CNET
Includes a free demo download and user opinions of the game.
http://download.cnet.com/downloads/0-10034-108-58918.html

GameGuide.com
A complete game guide including first-person shooter basics, weapons descriptions, walk-throughs, cheat codes, and easter eggs.
http://www.gamespot.com/gamespot/guides/oppose_gg/

Justice for all [JFA]
Includes screenshots, pictures, profiles, and downloads.
http://www.geocities.com/stryker_calhoun/

Planet Half-Life: Opposing Force
Walkthrough, tips, downloads as well as strategies for both the single player and online multiplayer version.
http://planethalflife.gamespy.com/opfor/