FNV 4GB Patcher - Allows the game to use 4 GB of RAM, which will make the game run more smoothly when using several mods, as well as reducing the number of potential crashes.
Mod Configuration Menu (MCM) - Adds a menu that allows you to edit the settings of many mods in-game. Whilst it's not required by most mods, a lot of mods need MCM to allow you to change their settings.
mods which improve the game's graphics or visual effects
NMCs Texture Pack - A big re-texture mod which improves nearly all of the game's textures. This mod has three different versions: a small version (for low-end PCs), a medium version (for mid-range PCs), and a large version (for high-end PCs). (The large version severely impacts performance, even on powerful computers, and may cause memory leaks, so the medium version is recommended.)
Pip-Boy 3000 Retexture - Higher-resolution vanilla Pip-Boy model. (Not compatible with mods that change the model of the Pip-Boy–may also be incompatible with the 'Faster Pip-Boy Faster' mod.)
Uncut Wasteland - Re-adds scenery clutter to the game world which was initially removed to improve performance for console players world. This mod makes the world feel a little more realistic and less empty. It also (optionally) re-adds removed NPCs.
Project Ultimatum - Allows you to force an enemy to surrender, inject someone with a drug, enslave someone, push someone, and more.
Cover Based Stealth Mechanics - Makes enemies have worse peripheral vision but enhanced vision over long distances. Also allows you to peek around corners (if you install the optional True Leaning file).
Rebalance adds all the features of the following mods (although optional), so if you have Project Nevada and did not untick the 'Rebalance' option, installing either mod is not necessary.
Perk per Level - Level Cap at 100 - Increases the level cap to 100 and gives you a perk per level, rather than a perk every other level. This does make the game a lot easier, though.
Max Level Adjustment - Simply increases the level cap to 50, 60, 75, 100, or 255 (depending on which version you download). (Do not use with the above mod, 'Perk per Level - Level Cap at 100.')
OneTweak - Allows the game to run in borderless windowed mode, as well fixing a bug concerning the cursor.
Console Rebind - Allows you to rebind the console key and/or disable the original key. Useful if you have bound the key you use for the console to something else, don't like the default console key, or don't want to accidentally open the console.
Melee Hotkey - Adds a hotkey which allows you to quickly use your melee weapon and immediately switch back to the weapon you were using.
Grenade Key - Allows you to throw a grenade by pressing a key. (Unnecessary if you use Project Nevada: Rebalance.)
Drastic overhaul mods and quest mods
These are mods which overhaul the entire game and add lots of new content, including new quests. These mods are usually not compatible with one another and may not be compatible with the other mods on this list. Use at your own risk.
mods which add lots of new content, in addition to new quests
After War Nevada - This mod lets you start the game as any faction. Adds new weapons, armours, foods, chems, and much more.
Fallout - Project Brazil - This mods adds a brand new story with a unique intro, new companions, new quests (including a new story quest line), new radio stations, new locations, voice acted dialogue, and more.
Fallout Who Vegas - Complete - This mod brings the Doctor Who universe into Fallout: New Vegas, with a detailed TARDIS (which can travel to any known coordinates–even to locations you've never visited before–has a large amount of corridors and rooms within, as well as having as a large number of interiors, modes, and more), unique quests, new enemies, new weapons, new gadgets, new foods, a regeneration system, space travel, space fights, and more. (Incompatible with Nevada Skies and may be incompatible with other mods as well.)
Tale of Two Wastelands (TTW) - Merges Fallout 3 and Fallout: New Vegas, allowing you to freely travel between the two wastelands. (This mod requires a legal copy of Fallout 3 with all DLC.) (Not on Nexus Mods.) 폴아웃3하고 뉴베가스를 한꺼번에하는 모드가 있다. 일명 TTW 모드라고 불리며 뉴베가스 기반이다.