As most of us will have noted, a lot of lore, names and places found in WoW's latest expansion are in some way altered versions of things in norse mythology. One may for example have noticed that the name of the last boss in the Halls of Lightning, Loken, is actually quite close to Loki, a god in norse mythology which becomes more evil as the years pass and who is a nephew to Odin. As a post in the topic about Ulduar got me interested enough to look up some additional information about Norse mythology, it became clear to me just how many names have been pretty much copied by Blizz. For your reading pleasure and because I can, I've looked up and sorted out a couple of them in this post;
Gjalerbron is an undead/Vrykul base of operations in northern Howling Fjord. Its name is probably related to the 'Gjallarhorn', which is the instrument the god Heimdal (who is comparable to Hermes, for those of us who know Roman/Greek mythology) uses to pass on information to the mortal world.
Nifflevar, a Vrykul village in south-eastern Howling Fjord seems to me to be a play on Niffleheim, which is the Norse underworld. Alternatively, the capital of the Sons of Hodir faction (Note that Hodr is a Norse god as well) named Dun Niffelem is also a possible play on this.
Utgarde Keep, the HF instance, seems pretty much literally taken from Utgard or Utgardar. The Utgardar are the lands surrounding a specific giant stronghold. And while we're on it; in Norse mythology the gods seem to be the protagonists with the 'giants' as antagonists. Loki, which I've mentioned earlier, actually more or less jests his fellow gods until he goes too far and is punished for his sins. He also ends up marrying a giant. One of the three children to come out of that marriage is Jorgmungandr, which is said to be a monstrous snake large enough to surround the entire world (which is called Yggdrasil by the way, a name of which I'm sure I've seen it before as well). Of course it's easy to make Jormungar out of Jorgmunganrd, which is the race of worms that are in a couple of quests referred to as 'sons of Loken'. While we're on it, note that Loken's brother and mortal enemy Thorim (Thor) sends you off on a quest to regain is hammer Krolmir (While Thor's hammer was named Mjölnir). Thorim's wife is named Sif, which is literally the name of the wife of Thor. In one of the quest lines involving Thorim, he mentions seeing a 'glance of Sif's hair' - the norse Sif had golden hairs.
Then there's Valkyrion (A village in south-western Storm Peaks) and the Lich King's 'Val'kyrs', which are both obvious references to the Valkyri, winged maidens who'se task it is to choose who dies on the battlefield and who lives - those who die are to become servants of the gods. And as we swap over to Icecrown we see the villages Ymirheim (Ilmr was a Norse goddess of which very little is known) and Jotunheim, the latter actually being close to Jötunheimr, which is the 'plane' the giants live in - Jötun actually means 'giant'. This place also serves as a place of trial for Vrykul; they fight eachother to the death to see who among them is found worthy to join the Lich Kings legions. The winners of this trial are named the 'Ymirjar' - the warriors picked to die by the Valkyr to serve as servants of the gods are named Einherjar.
Last but not least, there's Skadi and Ingvar, two bosses in Utgarde Keep. Skadi is also a giant and ex-wife to the god Njördr, while "Vár" is the godess associated with oaths and agreements - ironically enough, Ingvar is the one to announce the news of the Vrykul/Scourge alliance to the horde in a quest chain around Vengeance Landing, and possibly the sealer of this bond as well (seeing as the Vrykul's other proper leader King Ymiron is still 'asleep' by the time this announcement is made). Additionally, Ingvar is also the one to have made a deal with the devil; once you kill him in UK, he gets ressurrected by an undead Val'kyr to fight once more.
While I'm sure I missed some, it was interesting to see what came out of Blizzard's mixing machine when Norse mythology was thrown into it. They seem to indeed have done some decent research on this.