I second almost all of the aforementioned bands. Dub Buk, Drudkh, Nokturnal Mortum, Nagelfar, Negurã Bunget, Summoning, Morrigan/Mayhemic Truth being personal favorites.
Some more that I don't think have been mentioned:
Forgotten Woods - everything, but "Curse of Mankind" is their best imo.
Arckanum - "Kostogher", "Kampen" and "Fran Marder" (and the new split with Svartsyn is great too)
Limbonic Art - "Moon in the Scorpio" & "Ad Noctum - Dynasty of Death"
Hades Almighty - "Dawn of the Dying Sun", "Alone Walkyng", "Again Shall Be"
Silencer - "Death - Pierce Me"
Helheim - "Jormundgand"
Sear Bliss - "Forsaken Symphony" first and foremost. I have high hopes for their brand new one, "Glory and Perdition".
www.redstream.org has most releases by this Hungarian horde at a cheap price.
Lunar Aurora - "Weltengänger", "Ars Moriendi"
Lux Occulta - "Dionysos", "My Guardian Anger"
... at the top of my head.