Varg called himself Grishnack and named his band Burzum as a gesture to his own interpretation of Lord of the Rings, which is a slight twist on the 'misunderstood Mordor' idea, and ties in with his Nazi beliefs. Basically, Varg thinks the orcs drew from the idea of Scandinavian pagans and that Tolkien was writing about the victory of Christianity over heathenism. So, he used orcish as a little reference to that idea. Plus, there's the nice element of a 'secret', if you get what it means. Finally, it's a fucking cool word and it somehow greatly increases the profoundity of the statement: calling a band 'Darkness', as we all by now know, is ridiculous. It's too naive. 'Burzum' has a darker, more powerful ring to it as a word, and the act of translation somehow distances it from being silly. Because it is a profound mission statement if you actually go and try and do it. Nothing to do with Varg was a joke.
The idea of Sauron and co as maybe the good guys isn't unique to Burzum incidentally, there's a fantastic Running Wild song with a similiar idea and lots of killer broken English:
"A shoal of the knights of torture
Are hunting a witch to the dell
Sullen shades are raiding their squad
Church's minions fell
A black knight leads through the mire
And in Mordor she finds a new life
A life without pain and torment
No murder, no lies
Rancour, against all raiders
Beware, if you're renegade's hunter
Watch out in slough's haze
Vigilance, 'cause death waits
Recourse, to the traced
Be calm, they'll give you shelter
Restless, they fight for freedom
Never, they don't let you fall
Mordor"
(Running Wild-Mordor)
Running Wild might be a good place to start. Roughly 95% of their songs are about pirates. You'll probably want to start with the albums 'Under Jolly Roger' and 'Death or Glory', possibly the live 'Ready for Boarding' as well. I also can't see you getting away without getting 'Advance and Vanquish' by 3 Inches of Blood: it pushes serious metal as close to the descent into Spinal Tap as possible without actually crossing over, and it is simply a bitch of an album: I don't see how it is possible to dislike tracks like 'Axes of Evil', 'Deadly Sinners', 'Destroy the Orcs' and 'Fear on the Bridge'. Other things you may want to check out:
Candlemass - 'Epicus Doomicus Metallicus'
Cathedral - 'The Carnival Bizarre'
Danzig - 'Danzig' and 'Danzig II: Lucifuge'
Iron Maiden - 'Number of the Beast', 'Powerslave', 'Seventh Son of a Seventh Son' (probably the poppiest metal album that is really any good)
Judas Priest - 'British Steel' and 'Painkiller'
King Diamond - 'Abigail', 'The Graveyard', 'House of God'
Mercyful Fate - 'Melissa' and 'Don't Break the Oath' (these are often called Black Metal, but thats really only for the image and subject matter)
Nightwish - 'Angels Fall First'
Skyclad - 'The Answer Machine?', 'Folkemon', 'Irrational Anthems'
Therion - 'Theli', 'Lemuria', 'Vovin'
Nice varied selection completely off the top of my head. Should keep you going for a bit.