Elsewhere.org -- This site contains scans of boxes and manuals for Infocom games. It also mirrors or contains links to other Infocom sites. Finally it gives directions to the author's telnet site, where users may play the games online.
Infocom Info Site -- Everything you'd ever want to know about Infocom on one site. Historical timelines for company and games; information on all games with faqs, patch links, downloads; reprints of articles and so much more.
Infocom on the Commodore 64 -- The complete Infocom collection for the Commodore 64, each title listed with introduction, images, related links and comments area.
PRIZM -- This page has Z-Machine versions of InvisiClues.
The Encyclopedia Frobozzica -- This online encyclopedia is a reference of the names and faces you'll find in the Zork series. You can also download it in Acrobat format.
The Infocom Gallery -- If you're looking for high-quality scans of Infocom covers and props, this is the place to go. You can also find scans for lesser known release versions, too. There is a mirror up at http://www.fortunecity.de/wolkenkratzer/mond/236/index.html.
The Unofficial Infocom Page -- This site is the starting point for just about all of your Infocom informational needs. They've got game information, articles, and links for just about everything that's Infocom.