Fortunately for any crazy enough to attempt such, there are free and available art assets all around the internet. So I've made this thread so people can post whatever they find that may be relevant to helping people create these mods.
By way of contributing first, I'd say these assets, created for CryEngine 3, still look fantastic: http://www.crydev.net/viewtopic.php?f=310&t=76283&start=45
Certainly a nice question posed and some not too difficult conversion (once trees are figured out for Skyrim) should see brand new art assets for any would be modder to use, and I hope to see many more below this post. By way of suggestion, I seem to remember some very nice things being done for other regions originally intended as mods for Oblivion. Especially Morrowind, who's architecture was recreated in large sections.
