I designed this site to enable those of us who are having difficulty in solving Adventure / Colossal Cave to work together to solve the game.
This is not a hints site, and there is no spoiler space. Information is presented as fully as I can, though the information in the walk through tends to be less detailed and that in the object, people, and places pages to be more detailed. —afjbell —Adventure/Colossal Cave Home Page (Hypertext Walkthrough Index Page)
A useful site that breaks Adventure down into objects, places, and a walkthrough (all hyperlinked). The same site also similar treatments of Zork and a few other games.