Yes, I do indeed have a blog and have content to post! I spend more time running games and playing them than I do blogging and commenting, though I have wasted time on that recently. To make amends, I offer something constructive to the blogosphere: a blatant rip of Zak's NPC connection diagram from his excellent Vornheim the Complete City Kit.
It's a common trope that the population of megadungeons are divided into factions involved in a byzantine web of interconnected rivalries and alliances. This is necessary since otherwise the megadungeon inhabitants would react to the external threat of the PCs with united force, and there would be no rational for open by-ways allowing freedom of movement necessary for player choice. The PCs explore the megadungeon and are primed to take advantage of the splits to divide and conquer. Giving these relations substance allows for roleplaying and negotiation as a player choice.
The tribes in Caverns of Thracia, the factions within the Temple of Elemental Evil and even the disparate humanoid lairs of the Caves of Chaos in the Keep of the Borderlands have factional relations that PCs would do well to use. Here is a tool to assist you in brainstorming connections between factions in your megadungeon.
Click to download pdf
There are a few references to other megadungeon tropes. There are 'specials' like the "Talking Face" of Greyhawk Castle lore or the magic pools from In Search of the Unknown. There are pathways in the megadungeon that may provide access to many levels or otherwise hidden sublevels. Factions and beasties commonly enslave or eat one another in your typical "evul" dungeon. The dark gods, demons or creatures of chaos that may be worshipped in the depths below have their holy relics and sources of power that some may covet. No reference here is made to the "crazy wizard" or other reason that your megadungone exists (if it needs one).