this is a hella stupid thread but...

Here's a few, in no particular order:

Kayo Dot: The Manifold Curiosity
Agalloch:In The Shadow of our Pale Companion
Negura Bunget: Terasul De Lumini
Alcest: Pretemps Emerald
Ulver: The Future Sound of Music
Clad in Darkness: Nepenthe
maudlin of the Well: The Birth Pains of Astral Projection

Fuck, I have a million more.
 
Bethlehem's Tagebuch Einer Totgeburt is absolutely stunning in creativity for the time, as well as pure representation of sullen emotion.
That's just one, I'm out the door to work, so I'll get some more later.

Here's a few, in no particular order:

Kayo Dot: The Manifold Curiosity
Ulver: The Future Sound of Music

Metallica - Orion/To live is to die

Others are good, but I like other songs by those groups more.
 
I'll have a stab at this.. This is going to be fucking hard at points, as i'm going to try and pick just 1 from each band, a song that i have the best memories connected to, or just clicks with me the most.. I'll also try and note a few artists that haven't been mentioned.

Weakling - Dead As Dreams. (Coy will know why it's one of my favourite songs ever).
Esoteric - The Order Of Destiny. (Ffffffffffffffffffffffuck that was hard :()
Ulver - Sadface. (Even harder!).
Akira Yamaoka - Sickness Unto Foolish Death (probably the hardest choice for me overall).
Godspeed You! Black Emperor - Rockets Fall On Rocket Falls (extremely tough again).
Enslaved - The Crossing.
Neurosis - Stones From The Sky (another toughy).
Tenhi - Vilja.
Venetian Snares - Hajnal.
Tool - Rosetta Stoned.
Skinny Puppy - deep down Trauma Hounds.
Cult Of Luna - Echoes.
Opeth - Moonlapse Vertigo.
Akercocke - Shelter From The Sand.
Aphex Twin - Nannou.
Blut Aus Nord - Level-2 (Nothing Is Not).
Callisto - The Fugitive.
Deathspell Omega - II.
Camel - Migration.
Hawkwind - Hassan-I-Sabah (The live version on one of their most recent DVDs.. That version is fucking insane!)
The Meads Of Asphodel - Paradise.
Isis - Weight.
Radiohead - Morning Bell.
Smohalla - Les Yeux Du Temps.
Leftfield - Afrika Shox.
Mare - Sun For Miles.
Negură Bunget - Ţesarul De Lumini.
Primordial - The Golden Spiral.
Niroth - Seventeen.
Scott Walker - Hand Me Ups
WITTR - Cleansing.
Sleep - Dopesmoker.
 
I forgot to mention Comfortably Numb, and Wish you were here and of course Shine on you crazy diamond :D

Here are some more:

maudlin of the Well: Catharsis of Sea Sleep and Dreaming Shrines
Enslaved: Return to Yggradsil
Isis: So did we
Neurosis: Stones from the sky/Burn
Alcest: Le Secret
Ameseours: Bonhuer Ampute
 
^ Ya. And now for a load more.

Underworld - Born Slippy.
Esoteric - Passing Through Matter.
Ulver - Gnosis.
Akira Yamaoka - Theme Of Laura.
Enslaved - Convoys To Nothingness.
Peccatum - In The Bodiless Heart.
Alcest - Printemps Emeraude
Diagnose: Lebensgefahr - Transformalin.
Paatos - Sensor.
Sikth - Skies Of Millenium Night.
Tool - Disgustipated.
Sleepytime Gorilla Museum - Sleep Is Wrong.
Aphex Twin - Windowlicker.
T/M/K - Dopecity.
Ved Buens Ende - You, That May Wither.
The Mars Volta - Eriatarka.
Arcturus - Nightmare Heaven.
Manes - Terminus Rmx.
Porcupine Tree - Gravity Eyelids.
Neurosis - To The Wind.
Maudlin Of The Well - The Blue Ghost/Shedding Qliphoth.
Pink Floyd - The Great Gig In The Sky.