Here's an idea I wrote for Shadowfell, could work with Hades or the Plane of Shadow:
The Gloom Boxes: The Gloom Boxes are a collective term for the jails, asylums, and most unfortunately orphanages and refugee camps that simultaneously exist in the world and in the emotionally draining glooms of the Shadowfell. Designed to make the charges within their confines more tractable, many of these facilities are now haunted ruins left in disrepair.
Extracts from the memetic diary of Bryseis, known as “Rysse”, tiefling machinist – published in “Voices from the Hive” Issue 2, Revolution 12, Cycle 4.
Grey Sigil morning. The rain hits the panes like a Stygian drum. I have to start stocking up on food on my day off. The larder is sad and lonely and empty. A sodding void – so I finish off a half-bottle of Dispater-label firewater and pretend it's breakfast.
If I finally decide to buy food, I might as well remember to find a new tint of horn polish.
After their victory over the primordials in ancient times, the gods decided to end the threat for good. In concert, they forged a great ring, a containment for the remaining and free-willed primordials, a containment for the Elemental Chaos.
On this ring, 16 "outer" planes were arranged in perfect symmetry, corresponding to the alignment of its inhabitants (lawful, chaotic, good, evil, and differentiations between). The Outands, a 17th, neutral plane capped the trapped Elemental Chaos and hid it from the sight of the gods.
I would like to first thank David "Zeb" Cook and the entire Planescape team for coming up with the a way to make Gary Gygax's idea of other dimensions of existence even more thoughtful, funny, cosmopolitan and all together fun, along with many anonymous planewalkers over here who helped out a green like me. I would secondly like to thank the Dungeon Master's Guide II for inspiration for this idea in a relatively short, but insightful sidebar.