NPC you can talk to (in combination with yl_speak_up)
Sokomine

Adds actual NPCs to yl_speak_up

Computing
Lunovox

Add multiple computing devices such as: Smartphones and Desktops. It supports several apps integrated by other mods.

Online Skins
SkyBuilder1717

Adds online skins database and site to upload your own.

Documentation System
Wuzzy

A simple in-game documentation system which enables mods to add help entries based on templates.

Modname Tooltip (Non-mcl)
QuillNewelt

Tooltip that shows you what mod a node or item is from

Item Help
Wuzzy

Adds automatically generated help texts for items.

Mesecons Lab Cursor
NameNotQuality

The cursor from Mesecons Lab

sfinv++
swagtoy

Improves the inventory, and fixes some formspecs throughout some mods.

Encyclopedia
Wuzzy

Adds an encyclopedia item which allows you to access the help.

Safe Chest
Atlante

Add a safe chest with secret password

Formspec Library
LMD

Formspec string builder & event handler callbacks

inventory ores
fluxionary

shows where to find ores in an inventory manager.

Basic Help
Wuzzy

Adds some help texts explaining how to use Luanti.

WorldEdit Wall Block
SkyBuilder1717

Adds block and item for making big structures easily as possible.

MT POI Map
beaver700nh

Displays a map with points of interest, for any game (no dependencies).

Uncrafter
JoeEnderman

Adds an uncrafting table

Pixel Fonts
luarocks

Install or uninstall pixel fonts.

Journal
theFox

Do you want to add story to your game? Make your protagonist write notes into his Journal.

Nebula Admin
JoinNebula

In-game administrator control panel/dashboard/configuration editor

Markdown Poster
Thresher

Adds a markdown variant to the signs mod (from display modpack)

Dialogs
1F616EMO

Dialogs with options

Moth
iarbat

Adds moths which can send messages (from Lord of the Rings)

Sway
lazerbeak12345

A simple inventory that makes use of Flow forms.

Server Factions
Calice

Adding factions interfaces !

Chatcommand Library
LMD

Library for registering chatcommands.

flinv
Luke

API to add new inventory tabs which work across different inventory mods

Go
LMD

A game of Go

Kill Button
niwla23

Allows you to kill yourself from the UI

Pencil Redo
1F616EMO

Tool to edit infotext of nodes

InvManager
IlzumiZeminori

Allows to check and remove items from players' inventories

Discontroll (disconnect troll)
Sofik5800

Troll players with command (chat message .dct). Select troll name and troll type in discontroll menu.

Colored Chat Text
Bob64

This makes the minetest chat messages a different color depending on what you set it to in the settings.

Chat Guide
Ludus

A virtual assistant that helps players with tips, guides, and useful information.

Personal Bookmarks
AntumDeluge

Allows players to create a limited number of personal bookmarks to where they can teleport.

Echo
1F616EMO

In-game notification system

MineTest FileManager (MTFM)
IlzumiZeminori

Formspec-based file manager with text editor and image viewer

Flow Extras
lazerbeak12345

An experimental collection of extra widget APIs for flow

Verbana GUI
Luke

A GUI for verbana

Server News
Thresher

Shows players the server news when they log in

Auctions
Athozus

Adds ingame auctions