So, these trolls could either be humanoid (giant)s or monstrous humanoids. If you want to play up the troll part and not confuse players too much, go giant. Sure, they have tails and horns, but I think regular trolls are so beastial that they should all be monstrous humanoids, so go with either. Or fey, but fey are d6 half bab creatures and so you'd have to give them a lot of HD to make them challenging.
Norwegian trolls would be the classic evil Tolkien troll, with DR or regeneration to make them hard to kill, but obviously they turn to stone in natural sunlight. Give them a keen sense of smell, and if you want to really mine the myths, give them a constant detect the faithful (http://www.d20pfsrd.com/magic/all-spells/d/detect-the-faithful) style effect, but for followers of good gods (or potentially for followers of all gods?). I actually like the idea of this ability, it makes them interesting as some sort of blasphemous giant. Maybe they worship things older than gods, and that could give them protection from divine magic and some nature shaman style abilities. They'd fill the classic troll role regardless, and they'd be great as the allies of ancient evils like aboleths, quippoleths and Great Old Ones. I just love the idea of a troll inhaling deeply, and then turning to his allies. "I smell gods. Let's eat."
Icelandic trolls are similar, and seem to be the kind of generic giant that D&D giants are built on. They don't even have tails! There is something delightfully macabre about giving monsters a preference for children, but we all knew that already. Compared to the Christian eating norse troll they're rather dull. However, apparently some are nice - do they only eat bad people? If so, are they mocked like vegetarians by all the other trolls?
Swedish trolls could be a less powerful but more intelligent version, and they would be less evil, or possibly just more reasonable. They'd be less affected by sunlight though, but would still try to sty out of it, so they'd make good miners or traders, swapping ores or lumber or furs for jewelry. In an adventure, perhaps a group of them possesses a rare and shiny magical item that the players need - but they'll be surprised to discover that the "trolls" they've been warned about are happy to hand it over - for the right price. "Do you think that looking this amazing is easy? We need that +2 minotaur bane hairbrush to manage these luscious locks!"
Danish trolls are a potential PC race (regeneration 1 or less would hardly be game breaking - maybe they just recover more with rest), or at least a low HD creature that could feature in a social encounter, possibly directing players towards a more dangerous troll nearby. They could be rather secretive though, with racial illusion spells to hide their location, perhaps. The legend that they raise abandoned children is fascinating, particularly in a game if somebody gets the wrong idea and thinks they're stealing babies, and sends the PCs after them. If nothing else, "Raised by trolls" would be an amazing trait to have on your character sheet. I don't care what it does, I just write to write it.
(That valravn is interesting as a monster as well. We already have carrionstorms, but maybe a more powerful corpse could generate this undead raven, which then must seek a babies heart to regain it's former power. By transforming into a knight or a... wereravenwolf?)
I looked up trolls on wikipedia, and apparently lightning is the reason you don't see them in scandinavia today, so if you give them regeneration, use electricity to negate it. That on it's own gives them something interesting to challenge PCs.
Wow, thanks for linking this, it's always entertaining thinking of weird ideas, and you don't get much stranger than myth.