Tools for Mapping or Mapping is for Tools

Anyone who's been to Lord of the Green Dragons is familiar with this little ditty:

"Ten feet, twenty feet, thirty feet south. Passage turns east and west. Which way do you go?" "We go South." Stupefied look and momentary pause. "Okay. Bump, bump, bump." -E. Gary Gygax to adventurers in Greyhawk Castle, circa 1972. 

Sure it's an amusing anecdote, but it also does a great job of illustrating the shortcomings of using aural data to convey a visual experience.  Obviously, it's completely unreasonable to believe that the characters would have chosen to walk into the wall, but the players, sadly, don't see through their characters' eyes.  For failing to create an experience that would prevent the players from making an unreasonable decision, the DM must share the blame.  But EGG gets a pass; after all, it was only 1972, he was a rookie DM.

The most effective way of giving the players a visual experience is to give them a visual representation of what their characters see.  Therefore, lacking an arsenal of miniatures and dungeon tiles, I draw them a map. 

I hear you hardcore DMs scoffing, and, I admit, it's not a perfect system.  But it does a far better job of providing an immediate, visual experience for the players to react to than even the most efficient aural description ever will.  Sure, the characters would never be able to draw such an accurate map based on their first-person view of the dungeon, but it absolutely beats the pants off of this sort of confab: 

DM: You hear what sounds like children in distress on the other side of the door.
Player1: The ranger and the dwarf bust in the door the door while the rest of the party readies missile weapons and offensive spells.  What do we see?

DM: You see a large well lit room, approximately 40' by 50' with high ceilings.  There are two doors along the east wall and one on the opposite wall.  The north wall is lined with three alcoves.  There's a large table in the center of  room, tied-up on top of which are several small, squealing humans who resemble the farmer's kids.  Four very large, green men with rubbery flesh and protruding noses stand about.  You've clearly surprised them.
Player1: Trolls!  We've gotta' save the twerps; the ranger and the dwarf rush them brandishing--

Mapper: Wait a sec fellas.  How far apart are the doors on the east wall?
DM: They're about 10' apart
Mapper: Thanks, got it.
Player1:  Like I said, we charge them with--

Mapper:  Hold on.  Is the door on the west wall in the center of the wall or is it toward one side?
DM: It's about 5' north of center.
Mapper: Great.
Player2: My thaumaturgist will blast the trolls with--
Mapper:  Not just yet.  How about them alcoves; how deep and wide are they?  Are they evenly spaced?
DM and other players in unison: [groan]

Part of the problem is that you're translating data from one format--visual data--to another--aural data--so that someone else can re-translate it back to a visual format.  But even with DM mapping you're usually copying data from one sheet of graph paper to another, which involves counting squares on the DM map--4 squares by 5 squares--then counting them out again as you draw the map for the players.  Again you're translating visual data into another format--this time to numeric data--so that you can re-translate it back to visual form.

I like to eliminate the translation process entirely; just keep the data visual.  And to help do this I've dredged a couple of items out of my box of drafting equipment from my skool dayz:

Tracing paper: this stuff is awesome! A pad of it should come with every basic set.  Just slap a sheet on your dungeon plan, trace whatever the characters can see, hand it off to the players.  No more counting squares as they walk down long corridors, no more erasing misplaced doors.  You're working in the visual format throughout the process.  Added benefit for hardcore DMs who don't like giving the players too much info: the trace paper does not have a grid of uniform squares on it so players have to base estimates of distance and area on their own, imperfect visual assessment rather than the much more accurate method of counting squares.  Alternatively, normal bond paper and a light table accomplish the same feat.

Dungeon Module FU2: Marching Band of Sublime Precision

Buy the stuff by the pad or, for prolific and/or thrifty  gamers, you can buy it by the roll from your local art supply store.  Get a 12" x 50yd roll for ~$10 Canadian.  That's enough to map out 180 levels of your megadungeon!  

Circle template: That torch casts light in a 30' radius?  Slap the 1-1/2" circle on the map (assumes 4 squares to the linear inch; 5 squares you'll need the 1-1/8" circle), trace everything in the circle that they might reasonable see--obviously not around corners or through doors--and voila!  No more counting squares, ever.