The one map I finished was done listening to the 'Dead Cities' album from Future Sound of London.

I'll listen to almost anything I like when I'm mapping, but usually I tend to lean towards something that has some atmosphere (most pop/rock doesn't. 

... that is the question we should say.... Mapping (or playing) listening Death Metal, Hard Core Techno, or Alternative Fusion music, or others... is not an obligation... It's only a way to feel better...
It doesn't matter what kind of music it is, the only way is to feel good while playing or mapping...
But, if "good" music is RNB, Rap, or Soul... so it sucks... and all who love listening these ones sucks....
There's no compromise... Hard/Thrash/Black/Death Metal are definitively into the spirit of Quake... not others musics...
Enjoy !!!! 

I think I already said this somewhere on the internet (so of course everyone has read it) but I try to listen to music that fits with the style of map Im trying to make, Im not saying that I'll suddenly start listening to metal music or rnb or some shit like that, but I try to setup a playlist that gets me into the mood to build in a certain style.

FOr instace for crdm3 (the vendetta textured one - not released yet) I've been listening to lots of Catscan, lab4, Brain, and some dity DnB which I think makes me map eviler(tm)(c) and make more grimey dirty styles in crdm3.

Although tbh... I think I was listening to the carebares theme song when I lit it... argh! :D 

"everything I can't appreciate at the moment sucks" dance! 

**dances**

everything I can't appreciate at the moment sucks!

**dances**

everything I can't appreciate at the moment sucks

**dances**

everything I can't appreciate at the moment sucks

**dances** 

I think I was not very clear....
Sure Death/Black Metal is my prefered one, the more I'm playing...
While mapping, it depends on the context, and I'm not against listening something else like Dance, Techno, "Soft" Rock, or "top50 music", etc....
I'm fully opened to other music style, but I really don't like Reaggae, RNB, Rap, and Soul music... I don't like it but I appreciate some titles from guys like Eminem for example... but not all titles..
When I said it sucks, it was a little bit exagerated, shame on me if some guys were hurt....it was my opinion, and never I will blame the guy who listen these music.... I'll just kill them all in a deathmatch fight.... he he he.... 

noise/industrial/digital_processing here :D
and some black/doom metal from time to time :) 

Mr Death was sipping...
his three hour glass of tea
And while his bones were clicking,
he suddenly looked at me
If there was one question asking,
you'd like from death to see
For always thinking can hurt you,
for always feeling can make you scream to be. 

something quieter, ambient or instrumental. 

I can be very susceptible to what some might call an ironic combination of music, which in violent games would be something deep and meaningful.

My map Conundrum was highly influenced by the eerie ambient track running almost the whole time and the sort of whimsical thing was then added later, how that works fits the title :). I had the mil-techno Cannon from UT running much of Cats 2, both the Unreal and UT musics were great to pick from even if no one else gets the combination ... there's a sort of Zelda essence to the track each music version keeps going back to every time things start to calm down.

As to odd time signatures, when I first cranked up the Quake demo with King Crimson "Vroom" in the tray not even knowing why it was playing, it was like destiny. 

lol all bowie songs are muted on YT what a shit world this is