Infinite Chest
Dragonop

Adds a configurable chest that gives an infinite amount of something.

Mapserver
BuckarooBanzai

mod for the mapserver

Skygrid
ROllerozxa

Custom skygrid mapgen.

Lava + Water > Stone
1F616EMO

Cool Lava into technically special stones for easier cleanup

Rhotator Screwdriver
entuland

A predictable tool to rotate nodes

Classroom
rubenwardy

An easy way to manage students in-game, with support for bulk actions and macros.

scaffolding (flux's version)
fluxionary

scaffolding, to help in building projects.

Hard Trees
octacian

Require tools to break trees and introduce beginner-tier rock tools.

Balloon Bop
MisterE

Based on ExeVirus's Balloon Bash Ludum Dare submission, comes a minigame for Arena_lib all about Popping huge quantities of balloons and not letting them touch the ground.

Mystical Tools
liteninglazer

tool progression past diamonds and adds mystical staffs and wands

book_runner
fluxionary

run a command and put the output in a book

PVP Toggle
Impulse

Enables you to choose whether you want to PVP or not.

Nutra Paste
ApolloX

Low quality, but free, food source.

Custom Falling Nodes
TenPlus1

Tweak falling blocks to add custom controls

Nodeternal Darkness
Kimapr

make nodecore very dark

void grenade
GigaByte

add an void grenade

TPH's Wielditem
TPH

Wielded Item Events with Prepackaged Wield3d + Wielded Light Functionality!

Periodic Elements
ResendeTech

Adds the periodic elements

Node Touch Action
Neuromancer

Pass in a node name and a function, and every time a player touches that node, the function happens

UFO wreck
Irremann

UFO wreck

Random Cool
pl608

Adds random ores on lava cool

Public Inventory Plus
activivan

Adds a public inventory.

Colored Chat (Server Side Mod)
1F616EMO

Color Your chat message

Debug
LMD

Debugging on steroids

Utilities for Underch - extension pack
Hypernoot

Extend the Underground Challenge by miscelaneous utilities and change some recipes

City Block II
sorcerykid

Disables use of water and lava buckets within a designated area

Filter
sofar

A chat filter for servers, to warn/kick/ban on swearing

Item Displayed
michi16bit

Add displays

Minetest test framework
BuckarooBanzai

Provides an api to register test functions for integration-tests.

challenge
josegamestest

challenges to create route challenges or to train flight

Infinite Food Pouch
X17

Adds a pouch of food which can be eaten infinitely often

Lua Wand
IlzumiZeminori

Tool with programmable on_use

Points of Interest
Clyde

Mod to create or visit Points of Interest

Build Easy Box
epCode

A handy tool allowing the creation of large structures with minimal effort (in survival!).

Kitty/Kitto Ores
nemokitty9

Nemokitty9's own ore pack. Includes Tools!

Disable Build Where They Stand
LMD

Disables placing blocks at places where they would collide with a player

Areas' helper tools
rangeTonic

Convenience tools for Areas protection mod

CodeBlock
giga-turbo

Use lua code to build anything you want

Tomb Stones
Nathan.S

Adds many shapes and styles of tombstones.

Chat Logger
Flay Krunegan

Allows players to view the last 100 chat messages, also allows you to search for keywords