I always wanted a mod or DLC that adds Hircines hunting grounds, or something similar, just constant survival against a never ending world of monsters. Just an Eternal Battleground of monsters, nowhere is safe, there is no safe.
Adding the songs of Malukah would be great indeed.
A mod which make your chars actually speak out her or his line would be a nice addition. Currently they are quite mute beside the vocal battle and dying expressions.