NWOBHM:
Avenger: especially their first album.
Tyrant: they only released singles and such, but they have a great little anthology called Days at the farm.
The first two Tokyo Blade albums
Roxxcalibur - NWOBHM for Muthas; a great cover album of mainly NWOBHM obscure bands, it sounds good in itself and can guide towards other bands as well.
some new bands: Harbinger - Doom on You and The Metal Shakespeare Company - s/t
Epic heavy: Ironsword and Atlantean Kodex.
I imagine you're familiar with Brocas Helm, if not, get Defender Of The Crown instantly.
Doom Metal:
Sinister Realm and Argus, both american bands released strong self titled debuts last year.
If you like Briton Rites, you may wanna try the latest Hour of 13, same vocalist.
Minotauri, the finnish band.
Dawn of Winter and Lord Vicar.
Apostle of Solitude
Age of Taurus - these guys only have a demo, but it's so good I already see them as a future force in doom metal
rough Power Metal:
Helstar, Liege Lord, Meanstreak (the band of 3 actual wives of guys in Dream Theater), Cage, maybe some Marshall Law
Death Metal:
new Grave, Cemetery Urn and Immolation
Sadistic Intent
Grave Miasma
Black Metal:
Goatpenis - Biochemterrorism
For some merciless old school primitive black/death (think Archgoat): Blasphemophagher - …For Chaos, Obscurity and Desolation…
For some great blackened thrash/speed/heavy metal: Sodomizer
Thrash Metal:
Violator - Annihilation Process
Raped God - s/t
Trench Hell - try the split with Assaulter
Lair of The Minotaur - Evil Power
Hellish Crossfire - Bloodrust Scythe
Sauron - Thrash Assault
Wastelander - Wardrive
Some old underrated stuff: Carnivore, Morbid Saint and Anacrusis.