This is a list of albums, music scores and so on

Also I will point out one song from the album, but in some cases this song will be much different then the rest of the album so beware. The reason for this is that some of this albums are rather complex, so every song is different.

Also, most of this sounds horrible at first hearing, but after like ten times it finally sinks under the skin.

p.s. The reason why it took me so long to write this list is because, if I start to listen to this songs or albums I have to listen to them to the end, soooo... it took about 6 hours to compile this thing :(

I'll star with darker, nihilistic albums:

Godspeed you black emperor - F#A#∞ (Dead flag blues), Canada, post rock, I like to call it minimalist rock, but that's just me, also it inspired the film 28 weeks later, also the darkes album I know

Robert Wyatt - Rock Bottom (Sea Song), UK, let's call it jazz fusion, the second darkest/nihilistic album I know, the reason is that Wyatt, a famous drummer, lost the control of the lower part of his body and almost lost his will to live and made this depressing album

Yoshihiro Kanno - Tenshi no Tamago (Angel's Egg) OST (Memories of water, Different God), Japan, maybe the third darkest/nihilistic album

Igor Stravinsky -  Le sacre du printemps (Rondes Printanières), France, Ballet

Nicholas Lens - Flamma flamma requiem (Deliciae Meae), Belgium, contemporary classical (libretto is in latin :( )

Rock opera The fall of house of Usher by Peter Hammill based on the story by E. A. Poe (First two songs)

now strange:

Magma - K.A. (K.A. part1/4), France, zeuhl (mixture of invented language, progressive rock, jazz fusion and avant-garde music), prepare for this one!

Kayo Dot - Choirs of Eyes (Wayfarer), Boston MA, hard to explain but let's call it postmodern

Gordian Knot - Emergent (Fischer's Gambit), USA, instrumental technical metal/rock jazz fusion super group

Gentle Giant - Interview (Give it back), UK, progressive rock/eclectic 

King Crimson - Discipline (Indiscipline), UK, eclectic

and finally ambient or similar:

AshRa - The new age of earth (Sunrain), Germany, ambient proto-electronica

Andy McKee - Art of motion (Drifting), Kansas, ambient/folk instrumental fingerstyle

Soft machine - The softs (the song of aeolus), UK, jazz fusion

Ennio Morricone - The mission (On earth as it is in Heaven), Italy?, classical film score, he really should have gotten that damn elusive oscar for this one :(

Jan Garbarek - In praise of dreams (In praise of dreams), Norway, jazz/world music, 

John Scofield - Quiet (Tulle), USA, jazz down tempo

Kieth Jarett - Köln Concert (part I), USA, jazz

a lot of other things:

Death - Symbolic (Voice of the soul instrumental, Crystal Mountain, please pay attention to the lyrics), Orlando FL, technical metal, this is the only anti-religious song that I know of, maybe...

Rush - Hemispheres (La Villa Strangiato instrumental), Canada, progressive rock, know as the most complex progressive album ever, but who knows...

Spiral Architect - A sceptic's universe (Insect), Norway, let's call it progressive metal, but someone said that they have more melodies in this one album then some bands in their entire career. 

Devin Townsend - Ziltoid the omniscient (ZTO, By your command), Canad, conceptual progressive metal, he made the entire album by himself ;)