Ah yes, Amon Amarth. They of the 53-foot touring trailer with their album art plastered on the side! I remember seeing them at the Opera House in Toronto around '05, and then again here in '07 at Sounds of the Underground, where my buddy got his rib broken in the mosh pit during "A Thousand Years of Oppression." That was a good one. Funny that you bring them up - they are one of the few death metal bands I can think of that sound even a little bit like Bolt Thrower. Almost nobody in DM followed down that stylistic path, although of course AA draws on a great deal of the usual suspects also. Most of Bolt Thrower's imitators are actually crust & grind bands, go figure.
I lost track of AA around when "Twilight of the Gods" came out as I had started digging through all the old stuff. Maybe I am jaded (definitely) but the later records are too slick & samey. They definitely found their sound at a certain point and haven't shifted since. Amon Amarth's money album is unquestionably "Versus the World," though "With Oden at Our Side" gets second place - raw, intense & heartfelt, guitar tone is utterly nasty, riffs & changes are less predictable, songs are longer, Hegg's delivery has more variety.
If you like melodic death metal, a couple things.
I will skip the obvious stuff like Carcass (great) or In Flames (not very good):
The old Arch Enemy material (up to the first two Angela records. The Liiva-era material is great all the way back. Alyssa's era can be skipped and if you discovered them today, you'd be forgiven for thinking they are poser trash):
Dawn - the whole "Slaughtersun" album rules
There are plenty more but that's a start.
And for viking-themed metal the granddaddy of them all is of course Storm - "Nordavind" but you might find it a bit much: