Click to enlarge.
Don't get your suspenders twisted, copyright holder of record, this is just for educational purposes...
Y'all know how much I despise inefficiency. So I did this experiment to see exactly how much of the Caves of Chaos from the "classic" (translation: old) module Keep On The Borderlands I could fit on the map.
Answer: most of it.
The numbers refer to the number of each humanoid faction in that room--the color code on the right tells you which kind of monster it is.
If you've read the module even once, you can pretty much run any encounter in the caves using just this and the monster stats up to the point where the PCs start looting the dead (treasure is not listed).
Rooms where the room key gives some information not already on the map that's relevant in a fight are marked with a *. (Though generally this is not a lot of information--most of it is about as long as the notes that are written out in the margins of the map--"Gelatinous cube attacks if PCs are in room for more than 3 rnds and has treasure inside it" etc.. I just chose details that I could make fit.)
Room descriptions are obviously missing, but if you have any familiarity with the monsters involved you can pretty much make those up--there's a ton of filthy slimy guard rooms, the ones
with lots of guys in them are the common rooms and the ones with the bosses in them are fancy by local standards. The "independent" monsters live in bone strewn caves--shocking, I know. And if you can't figure out how to describe what the rooms where the evil priests and skeletons and altars over on the left look like, you should probably hang up your DMspurs forever.
One thing I forgot: locked doors. It'd be pretty easy to add a little "locked door" symbol to the map, though. If you have a spare half hour to scan the module and pop some on, I'm sure someone somewhere will be grateful.
(Another mistake I just noticed--for clarity's sake, the "orc head" note on the upper right should technically be orange, not red, but my screen's all screwy so I didn't notice 'til just now.)
Anyway, if I can do this in an hour-and-a-half using only the graphics program that came free with my mac to a dungeon that wasn't even designed to be "coded", the big companies should be able to get way more out of someone with, say, an actual graphic-design program and actual graphic-design degree and 8 whole hours to kill.
So remember: If you ever find yourself flipping back and forth when running a module even if it has absolutely nothing weird or complicated in it, it's because they're lazy.