seems like the place to ask for this sort of thing, i was in a tower once looking for peices of merunes razor, and just before i got to the top of the forsworn camp it was held in, in one of the towers i heard a horrible shreak, it repeated every 3 seconds, it was incredibly creepy, sounded like a mix of falmer and hagraven, any ideas? sorry about the innacuracy on where it is

I'm in the process right now of going through the same Forsworn camp, might creep the wife out if it happens to me

I've heard this often, usually just before I stumble upon enemies. It sounds like something dropping on the ground, like if I dropped a book, maybe a little louder. And it always seems to happen right after I pick something up. I just heard it after walking up a road and picking Snowberries. I heard it 5 times and then came upon a structure with an enemy posted....
I've heard this before and always thought I might have tripped a trap, but what kind of trap??
I hear it on a regular basis but I think it's a glitch with the noise your feet should be making when running/walking, instead of playing the normal steady rhythm thump,thump,thump of foot steeps it plays the sound of landing a jump instead. Used to happen a lot in Oblivion for me.
I have heard the sound of a troll breathing in certain indoor settings but never found a troll anywhere?
Spoiler The warehouse you find the skooma dealers in, in Rifton is a good example.
I have also heard a low humming sound emitting from magically inclined foes that fall to my blade, kinda like the same humming/ringing that nirnroot make but at a low frequency/tone? And only the NPC's with magic, I made sure to kill a bandit and a necromage together outdoors and lined them up side by side moving back and forth between the two just to make sure.