For those interested in the game and a minor nostalgia burn, the puzzle design document for Grim Fandango is available from its author!
There doesn’t seem to be anything truly substantial here that you can’t get in the game, except some photocopied drawings of some characters and scenes. It seems to mainly just explain how the puzzles are going to be laid out and so forth, and thus only acts as a kind of illustrated walkthrough.
I only just scanned it, since I never played GF long enough to beat it, and will eventually get around to it. Still, add it to your collection if that’s your thing (as it is mine).
WARNING: If you have not played Grim Fandango and intend to someday, or just don’t like spoilers, DO NOT download and read this document!