I have tried getting into some Dark Ambient projects but I'm disappointed most of the time. I feel the darkness is forced as in contemporary commercial goth or indus bands, the sound lazy, minor drone with samples going in and out... I don't mind playing it in the background while I'm doing reading for instance, but I don't take it very seriouslt to be honest.
Sorry if this has been mentioned, but to me the ultimate Dark AND Ambient release would have to be
Les Joyaux De La Princesse - Aux Petits Enfants De France - LJDLP - 1989
Dark drones with very interesting gritty textures far in the background, bleak spoken words from the Vichy state during France's occupation by the German army. It provides me with a rich palette of emotions, all darkened.