Originally Posted by Myrkrel
Any other recommendations for instrumental doom?

Maybe Omega Massif (Geisterstadt) or Capricorns (Ruder Forms Survive), though both are kinda more "post rock-y"/sludge-y (especially the latter band):
Omega Massif - Arcanum
Capricorns - 1969: A Predator Among Us

Also, Earth´s The Bees Made Honey in the Lion's Skull might fit the bill and it is a pretty unique doom-y instrumental album to boot, often it sounds like Wild West doom or something :
Engine of Ruin

As for me, besides the above Earth album this thread inspired me to listen to, Monkey3 - 39 Laps, which is quite good "new school" psychedelic rock and incidentally also an instrumental album:
Xub