Coil's first two "Unatural History" compilations particularly for the unreleased Hellraiser themes.
Anything you can lay your hands on by Megaptera, paricularly "Beyond The Massive Darkness"
Aghast - "Hexeri im Zwielicht der Finsternis" occult North European darkness on the fabulous Cold Meat Industry label.
Navicon Torture Technologies - The Church Of Dead Girls, a work of incredible power.
Prurient - "Pleasure Ground", I can't praise this highly enough.
Hope this helps