The only ones I know of is Therion's new album Secret of the Runes. Great CD. Speaking of vikings, has anyone played Rune? You play a viking and get to hack off limbs and heads and stuff; awesome game.
Don't forget enslaved. Especially the emperor split, vikingligr veldi and frost and eld (the first track is epic and about the viking raid on a monostary and crushing the skulls fo christians). Blodhemn has some viking stuff too...
Bathory is the quintessential viking band. Hammerheart fucking rules.
Amon Amarth rules! They're viking metal it seems, and they are really heavy. The album The Avenger is the heaviest one in my opinion. Check out the songs "God, His Song, and Holy Whore", "Bleed For Ancient Gods", and "The Last With Pagan Blood". Kick-ass tracks indeed.