some of these may have been mentioned before, but consider it backing to the suggestions. i'll trust you know how to obtain.
Kalmah: as have been raved about. bad-assery abounds.
Insomnium: i'd recommend all of their stuff. fantastic instrumentals, and very poetic lyrics. some of the best out there.
Mors Principium Est: it really doesn't get much more metal than this.
Solstafir: Masterpiece of Bitterness isn't very great, but Kold is fan-fucking-tastic. one of my favorite metal albums.
Amon Amarth: rooted heavily in norse mythology. straight up music for a man's man.
Veneficium: De Occulta Philosophia is one of the most beautiful black metal albums i've ever heard. killer drums and almost violin-like guitar parts.
Turmion Kätilöt: excellent production, very high energy and in your face sound. not the best musicians out there, but their sound is second to none. the finns on here should know exactly what i'm talking about. best headbanging on the planet.
2TimesTerror: the MC from TK's solo project. heavier on the synth and a little more experimental, but just as bad ass.
Sybreed: kinda hit or miss for me, but when they're good they're fucking good. two words: Doomsday Party.
Mortiis: The Grudge is a great album. everything prior is industrial, and weird ambient experimental folk craziness. great vocalist.
Fear of Domination: more good 'ol melo-death with a touch of synth.
Finntroll: i should hope you know of these guys. pirate metal in the most literal sense.
Moonsorrow: viking metal in the most literal sense.
Kiuas: a bit on the pagan side with power metal overtones, but minus the faggotry of power metal vocals.
Gamma Ray: power metal with the faggotry of power metal vocals. i can overlook that on the account of being able to shred like mad men:
http://www.youtube.com/watch?v=rvbguX1xxPs&feature=relatedCrionics: i can't say i really like a lot of their songs, but Black Warriors off of Neuthrone is cool as fuck.
that should do for starters. if you want more let me know. i should also note: i listen to many many genres (and metal isn't my favorite *shock*), so if you're looking to mix it up a bit i could help there as well.