fuck it, im popping in some Bohren & Der Club of Gore - Black Earth for my bedtime listening pleasure.
Yeah, the new Ulver album is great for it too.
Bark Psychosis - Hex
somewhere between post-rock and coldwave ambient with soft jazzy undertones, a bit akin to Talk Talk's Spirit of Eden in that respect. I love this album, it's the perfect definition of a nightly urban dreamscape, best enjoyed with half-numbed senses at 4'00 am or something. If you want samples I'll oblige later.
I'm mostly into Dark Ambient so, here is some of my favorites:
Desiderii Marginis (the best imo)
Kammarheit (especially The Starwheel album)
Tor Lundvall
Lustmord
Gustaf Hildebrand
15 Degrees Below Zero
Dark Water Memories
Djinn
Most other Cyclic Law stuff like Svartsinn, Northaunt, Visions, etc. are pretty much great too. I also agree on Klaus Schulze. And don't forget Variabel Parabel.
God Is An Astronaut are amazing although post rock and not ambient (at least the one i've heard - "All Is Violent, All Is Bright").