I've been spending some time on Freesound as of late and found some gems in the very. . . Very rough.
I'll be putting links here, with what I think they can be used for.
End music:
http://www.freesound.org/people/plagasul/sounds/1275/After the last fight, we need some music when the real credits roll (showing the team). I think this fits. If we need some more exciting music, that's possible as well.
http://www.freesound.org/people/Corsica_S/sounds/51425/I like this one as well.
http://www.freesound.org/people/Corsica_S/sounds/44829/...And this one.
Squirrel/Jellyfish/etc:
http://www.freesound.org/people/timgormly/sounds/152722/This can be used for a few different enemies.
Yeti:
http://www.freesound.org/people/ecfike/sounds/132871/This one could be used if it was turned down somewhat.
http://www.freesound.org/people/ecfike/sounds/132868/Same for this one.
http://www.freesound.org/people/ubecareful/sounds/20208/This could be used when not attacking.
http://www.freesound.org/people/reinsamba/sounds/48405/This could be used for when the Yeti starts to attack.
Portal sounds:
http://www.freesound.org/people/northern87/sounds/131100/This could be used when getting out of the portal for the new dimensions. Is does sound pretty machine-like, though.
http://www.freesound.org/people/zimbot/sounds/122972/This could be the sound of the portal itself.
http://www.freesound.org/people/zimbot/sounds/122982/http://www.freesound.org/people/zimbot/sounds/122979/These could be when you are in the portal and leaving the dimension.
Cave sounds:
http://www.freesound.org/people/ERH/sounds/30262/http://www.freesound.org/people/ERH/sounds/34012/http://www.freesound.org/people/PoisedToGlitch/sounds/7253/These could be a cave sound for another dimension or The End.
http://www.freesound.org/people/ERH/sounds/33987/Turned down, this could be a really nice Atmospheric sound.
Misc:
http://www.freesound.org/people/amliebsch/sounds/39046/This could be some of the random music, much like the C418 music that randomly plays. We need variety!
http://www.freesound.org/people/aesqe/sounds/49127/This could be used for the Yeti or some other creature.
http://www.freesound.org/people/D%20W/sounds/136696/This could be used with the dragon fire.
http://www.freesound.org/people/Robinhood76/sounds/66642/This could be used, turned down, for the Skyr dragon.
http://www.freesound.org/people/suonho/sounds/59353/A sound that could play in Gelidus Inferos. Gelidus is like a wasteland. Something like that coming out of no where would be freaky, but its a sign that life goes on.
http://www.freesound.org/people/Koops/sounds/20258/I'm not sure if Books already have a page turning sound. If not, this is for them and the Book of Lore.