A while back there was a thing floating around about the ten gaming books you'd most like to have if you could only have ten. I recently did some gaming/camping (my favorite kind of camping involves gaming and my favorite kind of gaming involves camping) so I got to actually make this decision. I didn't need ten. We brought:
tucked into Moldvay Basic was this. It came in handy.
We also brought:
Raggi's Random Esoteric Creature Generator.
The 1e DMG, but mostly because since we were camping I thought it might be useful to have something hard to write on.
We brought this:
Everything in this I either made or found on the internet! Here's a breakdown of the indispensable dungeon master tools in here:
Pages 1 & 2:
random swords and sorcery name generator
movement, encumbrance, light & vision, reaction roll chart, foraging & hunting, xp
Pages 3 & 4:
the Ravaged Ruins charts from Wilderlands of High Fantasy (worth three bucks for these two pages alone)
Pages 5 & 6:
MegaDungeon Area Name Generator
MegaDungeon - Doors
Page 7 & 8:
the Dismal Depths Trap Tables
random rooms and d100 things in a pit from here
Pages 9 & 10: