For everyone:
Just don't forget to say the wished game in your post, or you won't enter in the giveaway (I'll assume you already have them, and just wanted to help). If you would be happy receiving any of them (leaving the choice to me), that's okay.

I found that some Alva Noto songs work with fallout games quite well. I often listen to these songs while playing the game

http://www.youtube.com/watch?v=gCTfq3LMwG4

http://www.youtube.com/watch?v=EvHmRisve9o&feature=related

I'd like Fallout 2 if I win please

I'm surprised noone posted the desert theme from T2 yet. It should be good for the worldmap/ desert encounter/small town (Modoc, Ghost Farm, Redding etc.)

http://www.youtube.com/watch?v=sm-d7eSqxQw

Or you could use one of the tracks from this video, though I'm not sure where exactly it could be used

http://www.youtube.com/watch?v=s6aoTsKDfm8

These don't get the western wasteland feeling dead on, but I know I sure could listen to them playing Fallout.

http://www.youtube.com/watch?v=LjuuKlGln2I

http://www.youtube.com/watch?v=7lfXhK9ZtIo

http://www.youtube.com/watch?v=RScZrvTebeA

I might add a couple more to this if I remember.

EDIT: I forgot to say: Tactics, please.

Also adding this:
http://www.youtube.com/watch?v=fBva3nnCMvA
Among the whole album.

Again all the songs don't fit all situations, but it is definitely worth listening to.

I think Ry Cooder could make a nice soundtrack for the game
http://www.youtube.com/watch?v=X6ymVaq3Fqk
http://www.youtube.com/watch?v=JIwYGZlBw9Y

I'd like Tactics.

First off you should take some of the music from STALKER
http://www.youtube.com/watch?v=KRRGYEFZF4A
I love these Acoustic tracks

I'd like to suggest some music from Mafia for New Reno
http://www.youtube.com/watch?v=Tt8iveXlAHY&feature=relmfu
Also some more from Mafia would fit well
http://www.youtube.com/watch?v=Kwe2oxmg5xs&feature=related

Not really ambiance, but I think it goes well
Fallout 2 would be nice

Bump.
Since Fallout 1 isn't free anymore, you can choose it if you want.

Well, it's probably not something you are looking for but hey, it's amazing;
http://www.youtube.com/watch?v=RGME6jCwqw0&feature=related

But if you like it; Fallout 2.

Dark ambient right? Artists like Jesper Kyd and Lustmord come to mind

Both Dark Ambient and Drone Doom Metal are good choices.

More specifically, there is this music :
http://technologyofsilence.com/ (Technology Of Silence)
It's free (you can download the albums from this official website) and the theme is about a post-nuclear city so it certainly fits the Fallout universe!

http://www.youtube.com/watch?v=z3aXpvhBdGM&list=FLJqiSMGNtBBYIZ_9Cox5GTw&index=13&feature=plpp_video


and bookmarking this thread. so much useful info.

I'd say the music that plays in the 2300 AD era world map in Chrono Trigger.

http://www.youtube.com/watch?v=zTxBc_-XxmI

Can't go wrong with Escape from New York soundtrack! :)

Just about anything from the Nine Inch Nails Ghosts I - IV would fit.

Ghosts I - 1: http://www.youtube.com/watch?v=JA5rc4M-YrA
Ghosts I - 2: http://www.youtube.com/watch?v=T6R8GCX_wSs
Ghosts I - 5: http://www.youtube.com/watch?v=srJYQESO34g
Ghosts II - 11: http://www.youtube.com/watch?v=TvtYSJnm7Lc
Ghosts IV - 32: http://www.youtube.com/watch?v=GHkhwmSq9t8

I could just find all 36 tracks from the album. Like I said, pretty much the entire album...

(Fallout 2 please. Thanks!)