I'd been thinking "I really ought to return to developing some of the ideas I had about megadungeons". Perhaps even redo a lot of the maps I've done. And then I checked the Google Docs links for the "megamodules" and discovered that Google Docs, in the switch -over to Google Drive, completely mangled the few megamodules I actually did.
So maybe I *should* go back and redo everything from scratch.
The idea I've been leaning towards lately is a giant gaping hole left by a wormpocalypse that destroyed the former glorious empire. The worm's burrowings have exposed some gem veins and other sources of wealth. There's a new town founded nearby as part of a gold rush, and some of the upper levels have been explored and exploited, but the natural and supernatural aspects of the worm's passing have produced monstrous infestations as a side effect. Adventurers are scouring the cleared levels for scraps others have missed, and occasionally daring to delve deeper, in areas controlled by unknown monstrosities.