The world of Fallout 3 is enormous and full of stories, but this section proves there's always room for one more.
DCInteriors Project, by chucksteel
Transforms a lot -A LOT- of the buildings at Downtown D.C. from f'ing cardboard props into real buildings with interiors ripe for exploring. Includes dozens of cool, brand new collectible items. Just head to any area of Downtown D.C. and start kicking down doors.
Part of my junk collection at my Megaton house,
including a couple of wind-up toy robots
courtesy of DCInteriors Project
The Necronomicon Ex Mortis and Dunwich Expansion, by Satanabusjones
Extends the Dunwich building quest, including the infamous Necronomicon as an actual item with its own model and texture, and a nice ancient curse for good measure: Take the book with you and a gigantic Lovecraftian horror will be haunting your ass in no time.
A Note Easily Missed, by Puce Moose
An Evening With Mister Manchester, by Puce Moose
To sleep - perchance to dream, by Puce Moose
In the Shadow of the Swamp, by Puce Moose
The Mantis Imperative, by Puce Moose
There are two things that Puce Moose's quests have in common and make them just about the best quests out there: Clever and challenging puzzles like you won't find even in the vanilla game (always within the bounds of logic, they're all solved by pure reading comprehension and basic math); and stories that capture the spirit of Fallout 3 in a most brilliant way, especially that undercurrent of cruel, borderline absurd humor. And you always come out with a shiny new toy or two. They all start in a classic DLC fashion right when you activate them, with a pop-up message that gives you your first clue.
Firefly Ranch - Scary Quest Edition, by Kodiak888
A fortified house full to the brim with goods, a workbench, a Nuka Cola machine and everything you ever wanted in your house. It even has a secret mini-Vault. The best part of the mod, however, is the quest you have to complete in order to get the key to the ranch: With a handful of elements and in no more than 30 minutes, Kodiak888 here manages to craft an amazing horror story from a pretty basic premise: The transformation of the post-war world, as lived from within an underground bunker. The house is near Big Town, south of Germantown HQ; just explore it a bit and you'll quickly find the first clue to start the quest.
Devoured in Darkness, by Kentington
WARNING!! Small Point Lookout spoiler ahead: Remember the dream sequence? That crazy section with all the XXXX floating in the swamp and the trees on the sky and from which you came out with that XXXX on your head? Well, Devoured in Darkness is pretty much the same sort of thing, only it's and entire quest worth of that. It's probably the toughest quest of all, you move forward by pure trial-and-error through a series of deadly traps to the point you'll wear out the quickload key in no time, but it's worth taking a look if you like this sort of thing, with the surrealism and whatnot --It's about the most original quest you'll ever see. It starts with an S.O.S. signal in your PipBoy that leads you to a house right north of Minefield.
Cube Experimental, by SureAI
Heavily inspired in the movie Cube, this mod is one step short from a full-fledged total conversion, what with its completely new environments, a heavy usage of scripted sequences, gameplay unlike anything you've seen in the vanilla game and even its own intro cutscene with credits and all. The mod is basically a succession of deadly traps (sort of reminds of Portal, minus the portals and the humor) and can be really hard at certain points; but it's definitely worth checking out, if nothing else for its immersive atmosphere and mind-blowing artistic direction. When you activate it it starts like any regular quest, with its own map marker and whatnot.
Ambrosia Bells the Walls of Hell, by FrankSlimski
There's one thing that can't be denied about Ambrosia Bells, and it's the scope of its ambition; it even includes live-action cutscenes, go figure. You might want to play it from a dedicated saved game, since some drastic changes are bound to happen to the world as you know it. Go to the Megaton Common House, head up to the third floor, and take a seat. Someone will come and kickstart the quest in no time.
Acknowledgements & appreciation: To Bethesda, of course, perplexing amount of screwups notwithstanding, noone can deny they made an incredibly kick ass game; to all those sick freaks that sacrificed their social lives so we could enjoy the programming marvels featured on this guide; and to KamioKachu, my lab molerat during the creation of the piece.
And remember: Don't feed the Yao Guai!
That is all.