Watched Mononoke Hime again today (in IMAX!) and revived an old idea I've read somewhere of using the premise of the movie and apply it to Keep on the Borderlands: the Keep playing a similar role as Iron Town, and the Caves and its inhabitants as the woods and the beasts/spirits/kami. Using a modern reading of the old school alignment of law and chaos, place the Keep as Law and the Caves as Chaos: both with justifiable intentions, but locked in a violent conflict of interests that without interference will ultimately lead both to destruction. The players can help one side or another, or strive to find a way both can coexist.
When the box is released I will try to run a campaign using this idea, and see if it really works.