Due to lingual differences, modifications made and expressed in non-English language might not garner attention as much as their English counterpart. The List of Non-English mods contain the list of modifications with in-game text, manual, description, and related transcript solely in non-English language.
The list of those modifications are separated into two main category, released modifications (with sub-category of translated mods) and unreleased (work-in-progress). In addition, to speed the search for modifications in particular language, I added different text colors for each different languages.
RELEASED MODIFICATIONS
http://forum.wiwiland.net/index.php?showtopic=38784 - (translated: A pursuit of the bottomless bag) by Baka (French)
A quest mod centers on discovery of an artifact.
http://www.scharesoft.de/joomla/forum/showthread.php?t=10856 - (translated: Alexi’s Mageguild) by Alexis (German)
Voice acted quest mod what expands the Mages Guild with new characters and quests.
http://www.scharesoft.de/joomla/forum/showthread.php?t=36990 - (translated: Arielle's Weye Village) by Arielle (German)
Improvement of Weye settlement with small quests.
http://clandlan.org/teswiki/index.php/Oblivion:Mod_Black_Horse_Courier_Guild - by Dargu (Spanish)
This mod adds six main missions with the Black Horse Courier, plus three side missions. It also adds new NPCs, new buildings, new clothing (uniform), and a new city based on Balmora of Morrowind, the city can be accessed via a Silt Strider located just outside the Imperial City.
http://oblivion.forum.jpmod.net/viewtopic.php?f=10&t=148 - by tofu (Japanese)
Adds the new world of Carnac Peninsula which can be reached via a new ship at Anvil.
http://forum.wiwiland.net/index.php?showtopic=42806 - (translated: Moon Sugar Club) by Thanatos00 (French)
Want to involve in shady business other than Dark Brotherhood? Then this mod which allows player to become skooma dealer might be for you. The club offer services and other advantages for its members, provided one can complete the jobs of course.
http://www.planetoblivion.de/index.php?option=com_content&task=view&id=718&Itemid=72 - by Brachial (German)
Voice acted dungeon crawling quest mod.
http://www.worldofelderscrolls.de/?go=dlfile&fileid=76 - (translated: The Nightmare) by DienerRE (German)
Voice acted quest-mod, where you are kidnapped in your dream and have to beat several isles and dungeons to find your way back to Cyrodiil.
http://www.planetoblivion.de/index.php?option=com_content&task=view&id=1013&Itemid=72 - (translated: The Curse) by Henry (German)
Voice acted quest mod about a vendetta between two daedra lords.
http://www.der-orden.de.hm/ - (translated: The Order) by Xerxes and team (German)
"The Order" adds a new faction to Cyrodiil, created primarily for characters such as knights and paladins. It includes a fortress in the mountains of Cyrodiil, about 100 NPCs, dozens of new weapons and armor with some new 3D models, and a variety new quests. Act I (first part) of the mod has been released. Videos can be found http://www.youtube.com/profile?user=OrdenTeam&view=videos.
http://odd.newraven.net/ - (translated: Order of the Dragon) by Rung and team (German)
The mod start right after the end of Oblivion main quest. As the Champion of Cyrodiil, player will be faced with new challenges. It will feature many hours of gameplay, a fully functional desert, and many quests. Trailers can be found http://odd.newraven.net/videos/.
http://tesnexus.com/downloads/file.php?id=12119 - (translated: The White Gold Tower) by Fellan (German)
This mod revamps the Palace District and interior of White Gold Tower and features new quest, NPCs, and several hours of gameplay.
http://www.ei-der-zeit.com/board/index.php?page=Thread&threadID=2960 - (translated: The thieves of Leyawiin) by Good Psycho (German)
Should you become a member of the Thieves Guild, you can expect to discover the hideout of thieves in Leyawiin. A cozy place, with a new, small quest.
http://clandlan.org/teswiki/index.php/Oblivion:Mod_FeriaDLAN - (translated: DLan Fair) by Argoniano, Conchi DarkSmall, R3D and Zimnel (Spanish)
Adds small fairground camping, with a lot of NPCs exhibiting a lot of custom items, near Weye.
http://forum.wiwiland.net/index.php?showtopic=43525 - by Morgano (French)
Southeast of Anvil is a ruin, Fremleyan in the ancient language, which hovers a mystery for centuries. Maybe one day a seasoned explorer will he have the courage to risk the dangers of Fremleyan...
http://oblivion.forum.jpmod.net/viewtopic.php?f=10&t=147 - by HISSSSA (Japanese)
Revamps the appearance of the original horses in Oblivion.
http://www.planetoblivion.de/index.php?option=com_content&task=view&id=1439&Itemid=72 - (translated: Jakhar’s Scaffold) by Jakhar (German)
Dark quest mod about Bravil’s headsman Jack who is also a collector of decent (new) weapon sets. The quest takes place in Bravil.
http://oblivion.forum.jpmod.net/viewtopic.php?f=10&t=186 - by Arma (Japanese)
Fixes some "flaws" with the Arena of the Kvatch Rebuilt mod.
http://www.planetoblivion.de/index.php?option=com_content&task=view&id=770&Itemid=72 - by Jakob (German)
Voice acted quest mod about a new isle in the Niben-bay, where a new faction (necromants) has settled on with not the finest intentions.
http://forum.wiwiland.net/index.php?showtopic=33772 - (translated: The Bestiary of Noah) by Thanatos00 (French)
A mod for the adventurer-type player. It centers on a quest to recover ingredient for Noah who is waiting in his home southeast of the Arcane University in the Imperial City.
http://forum.wiwiland.net/index.php?showtopic=37826 - (translated: The Mystery of Ra'Jiska) by AshKhan (French)
This mod adds a castle (part of an estate) located near the road to Cheydinhal and allows players to become its owner. The castle is habitable and it is possible to hire servants. There is a main quest, side quests, and many surprises.
http://www.scharesoft.de/joomla/forum/showthread.php?t=3015 - by Diener RE (German)
This mod features a new city "Marodan Osdakal" located in the Abecean with over 30 quests and new NPCs.
http://oblivion.forum.jpmod.net/viewtopic.php?f=37&t=36 - by mpc (Japanese)
Allows you to recruit NPC in-game as companions with additional features to manage them. The Japanese counterpart of CSR. OBSE required.
http://clandlan.org/teswiki/index.php/Oblivion:Mod_Necromancers_Guild - by Mc van Fledermaus (Spanish)
Allows you to join the rank of necromancers. This mod adds several new quests, armor, creatures, and the Guild of Necromancers itself into the game.
http://www.tesnexus.com/downloads/file.php?id=4380 - by Takyon (Spanish)
More than just an overhaul. This modification changes almost, if not, everything in Oblivion. From tiny aspect like the "annoying message", torches, trap, fatigue, hunger, saddlebags, the effect of armors, to the effect of weather on your character, new races and class, new type of enemy, combat behavior, and the rest is up to be discovered. Also featuring a more dangerous combat with variety of possible injuries.
http://clandlan.org/teswiki/index.php/Oblivion:Mod_ORM_Rebuild - by Takyon and Poison (Spanish)
More or less similar to OOO, or perhaps FCOM. It is a massive overhaul. It adds a lot of new and diverse content, ranging from aesthetic, proprietary systems, enhancing challenge, rich interaction, strategy, new enemies, items, quest, and so on.
http://clandlan.org/teswiki/index.php/Oblivion:Mod_pociones_colores - (translated: Potions color) by Argoniano (Spanish)
Changes the appearance of every type of potion bottles into 10 new colors, along with their corresponding icons.
http://theelderscrolls.info/?go=dlfile&fileid=205 - (translated: "Springville") by Trebron (German)
Quest mod what brings the Quelldorf-village to the well of the Larsius river.
http://www.tesnexus.com/downloads/file.php?id=20421 - (translated: Kingdom of Nottingham) by Snake_71 (Italian)
A mod featuring new city with custom meshes and textures. Shivering Isles required.
http://clandlan.org/teswiki/index.php/Oblivion:Mod_Samurai - by Marcos Armengol (Spanish)
This mod adds new Samurai style light armor for men and women, and many weapons. All new items can be found at the Imperial market, and Fighter's Guild in Bruma and Bravil.
http://tesnexus.com/downloads/file.php?id=26824 - (translated: Shipping in Cyrodiil) by Fellan (German)
Based on "Rowing" and Jason1's "Pilotable Pirate Ship", this mods add new sailable boats and yacht with improved script over its predecessor. It also adds buyable equipment for the boats and yacht.
http://www.tesnexus.com/downloads/file.php?id=25026 - (translated: FG Symbol) by Snake_71 (Italian)
This small mod adds and changes the symbols of all Fighters Guild. Now every city's guild has its own symbol and sign with engraved name.
http://www.tesnexus.com/downloads/file.php?id=25123 - (translated: Imperial City Road) by Snake_71 (Italian)
A simple mod that changes the pavement of Imperial City.
http://www.tesnexus.com/downloads/file.php?id=18948 - (translated: Lost History) by Snake_71 (Italian)
A quest mod to gain the possession of new custom armor and weapons.
http://theelderscrolls.info/?go=dlfile&fileid=257 - by Ryan (German)
Voice acted group adventure, where you go with four NPCs on a treasure hunt.
http://andoran.clan.su/ - (by Andoran Team (Russian)
Featuring archipelago consisting of three major islands with three different cultures including architectural styles. The island also have several forts of the Imperial Legion. Andoran is actually a series of mods, in which the quest mod Andoran: AXIS was already released while Andoran: Prologue is a work-in-progress. A video can be found http://www.youtube.com/watch?v=ebI0McEcPmY, and the thread on Beth forum is located http://www.gamesas.com/index.php?/topic/1107446-andoranwip/.
http://www.planetoblivion.de/index.php?option=com_content&task=view&id=1611&Itemid=72 - by Master of Worlds (German)
Voice acted quest mod taking place in a ruin on the Shivering Isles.
http://www.tesnexus.com/downloads/file.php?id=22555 - by Eldarie (German)
This mod aims to add Valenwood province complete with cities, villages, dungeons, and more to fill. Shivering Isles required.
http://www.worldofelderscrolls.de/?go=dlfile&fileid=149 - (translated: Vampire Quest) by Rung (German)
Voice acted quest mod, where you start as a member of the Black-Lake (vampire)-clan.
http://www.planetoblivion.de/index.php?option=com_content&task=view&id=951&Itemid=72 - (translated: Improved Mages Guild) by Rung and team (German)
If the player in vanilla Oblivion game has been appointed as Archmage, there would be no more quests available and otherwise to get considerably, rendering Archmage position a bit "pointless". This mod changes that.
http://blackocean.ucoz.ru/ - (translated: Black Ocean) by Misha and team (Russian)
Black Ocean tells the story of a powerful force who woke up after millenia of sleep, which even the death and the Daedra fear. Only a pure-hearted warrior can put an end to its menace. It begins with mysterious events taking place recently in Tamriel. Featuring a huge number of new literatures, lots of custom models, new locations and a fully furnished cottage for the player. Black Ocean is split into episodical releases similar to Adash.
http://www.7roads.ru/forum/index.php?showtopic=2529&st=0 - (translated: South Wall) by Usher (Russian)
An expansion for the expansion Shivering Isles. A new small settlement, the center of which is the tavern "South Wall", awaits the traveler.
TRANSLATED MODIFICATIONS
http://www.scharesoft.de/joomla/forum/showthread.php?t=18642, http://www.scharesoft.de/joomla/forum/showthread.php?t=23231, http://www.scharesoft.de/joomla/forum/showthread.php?t=28572 - (translated: Adash - City of Magic) by LordKain (German)
Adash the city of magic, features a new worldspace, which takes place beyond the borders of Cyrodiil and Tamriel to the far west end of the sea. The thread on Beth forum is located http://www.gamesas.com/index.php?/topic/1092637-relz-adash-city-of-magic/.
http://www.nehrim.de/ - by Arandor and team (German)
Nehrim is one of the most extensive Total Conversions for Oblivion. It contains a completely new, hand-built world, numerous quests, many exciting dungeons, new weapons, armors, items and spells, full German voice acting, a new soundtrack and much more. The thread on Beth forum is located http://www.gamesas.com/index.php?/topic/1116846-release-nehrim-at-fates-edge-english-version/.
WORK-IN-PROGRESS
http://forum.worldofplayers.de/forum/showthread.php?t=341608&highlight=floranius - (translated: Florianus Garden of Winds) by Muecke (German)
Voice acted quest mod with a new village and land-space.
http://www.egg-of-time.us/board/index.php?page=Thread&threadID=4515 - (translated: Irthinia – Forgotten Isles) by Momo (German)
Quest mod with desert-like islands, civilization, and multiple quests.
http://www.tesnexus.com/downloads/file.php?id=25169 - (translated: Kvatch Resurrected) by Snake_71 (Italian)
A new Kvatch, with new meshes and textures. A preview video can be found http://www.youtube.com/watch?v=qETUY3bW3dc.
http://www.thelostsouls.ucoz.ru/ - (translated: The Lost Souls Isle) by ХАНТЕР13 (Russian)
A devastating attack by mysterious creatures on Anvil was successfully repulsed, but cost the life of an Imperial Legion captain whose son vows revenge. The Champion of Cyrodiil was summoned, and the journey starts on an island of constant pitch darkness, with no sun and no moon. A preview video can be found http://www.youtube.com/watch?v=Q31hZ4yKV24.
Skyrim is a global modification which aims to feature vast territory (the size of the new territory will be about 2 / 3 of the total area of the province of Cyrodiil in the original game), located behind the northern border of Cyrodiil. Full compatibility with the physical borders of Cyrodiil, as well as the minimum the dependence of all that is happening around the character from its level of development.
NOTES
A Mod Translator tool which can perform semi-automatic translation can be found http://www.gamesas.com/bgsforums/index.php?showtopic=1041309. Only English-German translation is available currently. I am unsure about the results of the translation, but it might be worth trying.
Additionally, if you aren't familiar with the languages and want to understand more about the description, the use of http://translate.google.com/translate_t is recommended, it's not perfect but at least it should give you the basic idea of the mod.