So, are there any mods that help make the world a lot darker? And I don't mean like just turning down the brightness or sunlight dark, but like actually changing the game world so that it looks much darker and less happier than it is now. Think Dracula meets Morrowind meets Oblivion, for the sort of atmosphere that I am trying to convey here. I am basically just tired of the bright, shiny, and happy-go-lucky atmosphere that Oblivion has, and if some mods (texture packs would probably do the bulk of the work I assume) can change that into a darker and less happy one, it would be greatly appreciated if I knew what the names of those mods were.

I would do it myself, but I'd rather not if something like it has already been done to some degree. (I already make my own custom textures and what not)

There's a version of OBGE (Oblivion Graphics Extender) that turns the world into shades of gray. Fearabbit also has a Darker Cathedrals texture pack that makes cathedral interiors darker and more Gothic (really beautiful, IMO). I don't know of anything else, though...

There are two or three mods that change the Imperial city to darker, grimier textures. Search TESNexus.Obviously there are also mods that make nights darker and dungeons darker. Can't think of much else right now.

What, exactly, are you looking for? Light level mods? There are plenty of those. Or texture replacers? There aren't too many of those.

^^ Anything really.

Are you expecting texture mods, or do you want texture mods?

Because I don't really use any so I of course wouldn't recommended any (because I'm not familiar with them, not because they aren't good.

If you're speaking about setting, quests, ambiance, characters, etc. then here are a few examples:

Enhanced Daedric Invasion (Dagon's invasion is more hellish)
Vector (disease spread, become worse over time, etc. like in real life..... so you can start an epidemic if you want.)
Blood and Mud ( an overhaul on Bravil making it more dark and seedy.)
Quest mods by the modder Simyaz (they're usually pretty dark)
Windfall (An expansion type mod with a new land and 30+ quests. Some of the quests are pretty advlt and mature in nature.)
Integration (The main quest itself might look like a fluffy, happy-go-lucky, enriching experience, but.... There is a lot of grays, character development, back stories, and some of the quests can be pretty damn dark.)
Blackwood Company (join the Blackwood Company instead of the Fighter's Guild)

You can find some more dark quest mods on the http://knol.google.com/k/toql-the-oblivion-quest-list, though of course you'd probably want to steer away from the ones with "Knights", "legion", "paladin", etc. in their names for obvious reasons.

EDIT:
Duhhh, how could I forget such a popular mod:
http://www.gamesas.com/index.php?/topic/1069109-relz-oscuros-oblivion-overhaul-133/ (A major overhaul making the world a lot more deadly, adding some pseudo-quests related to factions from other provinces (Morrowind Slavers, Skyrim marauders, etc.), as well as some other things which might help to 'darken' the world.)

AmpolX's texture replacers sound like what you are asking for.