I'm a giant perv, so be warned.
My dream mod would incorporate nude mods, sex animations and transformation mods that undoubtably don't exist to transform skyrim into something akin to the text games Nimin: Fetish Fantasy https://www.furaffinity.net/view/9830293/ and Corruption of champions http://fenoxo.com/play/
In both of these games you can have sex with nearly everything in the world and almost anything you do has a chance to transform you in some way, either to add sexual characteristics (give you a penis if you're a girl, give you boobs if you're a guy, or to increase the size of either) or to change your overall form (give you demon wings/horns/hooves, or wolf fur, facial features, etc). They even take it to the point where you can be impregnated and carry to term (neither force you to care for the children, CoC has the children run away as soon as being born, nimin delivers them to a day care). They're kind of like nethack where the intent is for it to be wank material rather than just kill you.