The non-interactive fiction department of Infocom.  The Zork gamebooks were very similar to Endless Quest books (right down to the sucking part) but for a little kid I guess they are exciting.

The novels are a different story.  Written by Craig Shaw Gardner, Robin W. Bailey, and George Alec Effinger, all these books are excellent pieces of fiction based loosely on the games of the same name.  Like the corresponding games, Wishbringer, Zork and Planetfall and very funny with the same sort of tongue-in-cheek humor as is found in the games.  The others are slightly more serious but all are well-written adventure stories.  I was unaware of the existence of Lost City of Zork until recently and I'm not sure of its significance as it appears to be the only book not directly based on an Infocom game.