|Not a solution to Boredom
The issue that it beings to mind are the inherent limitations of Megadungeon play, and the tendency (one I see myself a lot) of dungeon delve focused games to become repetitive and boring. Eventually it doesn't matter if it's giant rats and copper coins or Demons guarding a rack of magic platinum skulls (or War Haints protecting a still operational 6-inch gun in my game): the kick down doors, avoid the trap, defeat the baddies treadmill will cause sleep in most - including the GM.
To that end I've been considering ways to split up the monotony, these encounters would be timed with player progress into the dungeon, when faction disputes start heating up or something similar.
1) Set Pieces - These are non-location keyed encounters, instead being event or time keyed that create turmoil, especially within the explored areas of the dungeon. A set battle is good - get the players feeling good about something (say hauling back a hoard) and provide them with some weaker back up (the local militia or a coalition of NPC parties) then spring some kind of counter force on them. Suddenly it's not a dungeon delve, its a battle with the players playing both generals and shock troops.
I think this works best on a pre-set schedule e.g. "The forces of Mugyax the Horsewizard will attack the shrine of the Deep Dwarves in Session 6, both sides will try to enlist players." With a set schedule there's no danger of getting sidetracked, and if the players ignore the issue - of course consequences occur (no Deep Dwarf of Magic Horse allies at the least).
2)One Shot - Give the players control of another faction within the dungeon or nearby and put out a stake that matters (destruction of a useful resting spot in the dungeon say) then hand out the pregens - perhaps the Mummy King and his Wights down on Level 7 or something similar for a focused, goal directed mission against another faction that will determine who's sending a expedition up to the explored areas or if the river will be diverted to flood some key areas the players care about.
Anyway I think something needs to be done to keep Mega-dungeon play fresh, and these are the ideas I've come up with and will be trying.
Also check this Mega Dungeon design philosophy out - it's cool !