I had an idea about the distribution of high-level NPCs and villains.
I've said in the past that I like keeping the number of "leveled" characters low, mostly limited to player characters and their henchmen. But on the other hand, I like the way random castles for high-level types feel. Wayne's post a few days ago about the implied setting hidden in the tables and procedures of Underworld & Wilderness Adventures sparked a discussion on the ODD74 forums; one of the topics was the way the castle inhabitants seem to behave like the encounters for questing knights in Arthurian romance.
I think the only "real" leveled characters should be henchmen. Everyone else in the known, settled territories can be the equivalent of a given level, but aren't actually a leveled character. Just set the hit dice and what abilities the character can access, like "4 HD swamp witch can make potions for any spell of 1st or 2nd level."
But how to set the hit dice? For dungeons, just use the dungeon level (or wandering monster level.) For wilderness encounters, wanderers and hermits have 4 HD, leaders have 6 HD, distant castle owners have 10 HD. Halve these numbers for magical types; make patriarchs and heresiarchs halfway between the two. For settled areas, halve these numbers again.