A cool device, I thought. But DS didn't actually have a book for us to sign there at the table.
As campaigns come and campaigns go, I'm working on a new dungeon. So now I've got the chance to steal the Desert Scribe's conceit and take it further: get a physical book that the players could sign as their characters. Especially as I intend to run this dungeon for a variety of different players, the book itself could be an interesting artifact that people could look forward to reading and signing.
Next though is what's the megadungeon's origin? The old "ruined dwarven mine, over run by humanoids" won't cut it. And while "a wizard did it" always works, it's been done.
So, who else would be tickled to have a guest book at every entrance - the same guest book, no matter the entrance?
Well, the Trickster. Perhaps I've known Loki from stories like this where the Trickster side shows through, instead of the recent movies that depict him more forthrightly evil. But if Loki or whatever stand-in I pick for the Trickster archetype (Coyote?) were to create a "huge ruined pile" (rip), the possibility of a fun house dungeon would be rather large. Perhaps the Trickster even (ala Loki and Baldr) planned to trick others into a conflict, say a god of Light and a god of Darkness. It's a start. Now, whether that's step 1 of "how to host a dungeon" or some thing that happens to the Dwarven Fortress is another question.
Not having a world or a pantheon yet (and plenty of campaigns never need them), I'm tempted to go for the Baldr and Loki conflict as a more contemporary event; contemporary in the sense that it didn't happen a mythological age ago but one of the precipitating events for the local apocalypse and collapse of empire. Would the dwarves of the world be followers of the Trickster, so that there is no end of odd mechanical strangeness in the tunnels they dug for the millenium's most epic practical joke by the Trickster? And what other factions and beings would be attracted to the power and magic left by the gods?
Of course, what are the consequences of signing and not signing? I'm thinking that there will be specials and factions that react positively to those that have signed the book truthfully. And of course, some that won't. Which and why? Good questions.