Sinjin's Ultimate Online Adventurer's Guide

Detailed walkthrough with over 500 screenshots, cheat codes, beginner's introduction, tips and all treasure locations.
http://www.the-spoiler.com/Sinjin/INDY/indywalk.htm

IndyJones.Net

General game information, screen shots, cheat codes, forums, and links to demo and gamepatch downloads, walkthroughs and related sites.
http://www.indyjones.net/

Indiana Jones and The Infernal Machine

LucasArts official site. Includes hints, tips, demo, patch, and information about the creators.
http://www.lucasarts.com/products/indy/

The Spoiler Center

Cheat codes and complete walkthrough by Dusha.
http://www.the-spoiler.com/ACTION/Lucas.arts/infernal.machine.1.html

CheatingPlanet

Cheats, codes, and hints for the demo.
http://www.cheatingplanet.com/cheats/pc/2167.shtml

Neoseeker

Offers screen shots, a discussion board and links to reviews.
http://www.neoseeker.com/Games/Products/N64/IndyIM/IndyIM_reviews.html

eLook Gameboy Color

Quick summary of codes and cheats.
http://www.elook.org/games/cheats/gbc/552.shtml

UGO

Description, screenshots, walkthrough and cheats.
http://indianajones.ugo.com/games/infernal_machine/