My Mulch
Don

Turns leaves and other items to mulch blocks

Engravings
Taren

Adds multiple engraved blocks and benches to make them.

Renewable Fireflies
mecha_moonboy

Registers an ABM on some ground blocks that spawn fireflies if certain criteria are met.

My Torches HD
Don

Changes default torches to ones that burn out and cause damage

Glostone Building Blocks
Wovado

Adds basic glostone-based building materials

New Biomes
Arkatron

If you like underground biomes, this thing is for you.

3D Armor Mobile
LandarVargan

Adds a command to bring up a formspec that allows mobile users to put on armor

LDF Race And Parkour
lister

Race/Parkour Timers and Record Tables

Tac Nayn
GreenXenith

Adds Nyan Cat's evil twin, Tac Nayn (and a gray-scale rainbow).

New Horizons
Hi_World

Adds 4 new biomes and TONS of new blocks!

Aqua World
NovaX

Generate an underwater world with deep water, sand, and sandstone.

Useful Contraptions
theFox

Some useful contraptions / machines.

Gates (wider)
Sokomine

Wide gates for easy walking through and keeping cattle inside

Cottonseed Oil Fertilizer
1F616EMO

Powerful fertilizer from cotton seed

Basket Cooking
1F616EMO

Cook all stuffs inside a basket with electric furnaces

Blood Bane Sword
Blocky Player

OP sword for moderators. In memory of an old teacher, who had a mod similar to this on a private server.

Advanced Biome Decoration Modpack
EmptyStar

A collection of advanced biome decorations

Lava Particles
karlexceed

Adds some spark particles to lava pools

BitChange
Krock

Money items for your world. You can mine bitcoins. Sort of.

Item Holders
Jose_ManuelS18

Adds 'Item Holders', blocks that hold your items in display, also provides a API.

Node roads
MatyasP

Add much of one-node roads and crossroads, road bridges and slopes

Cthulhu eye boss
Giga_M

Cthulhu eye boss adds

Mesecons Stealthnode
Clyde

Register your own Ghoststones.

Hoverboard
mazes

Hoverboards

Unified Hammers
Linuxdirk

Various hammers that can be used to crush nodes.

Ubertool Mod
HartRend

Provides a combination pick, shovel, and axe tool capable of extreme function. Tool is also illuminated.

Anarglass
VerdiSchubert

Some kinds of glass nodes

Mycorners
Don

Put decorative corners on blocks.

morebiomes
mzs.112000

A simple mod adding a few biomes to Minetest Game

Color Blocks
mt-mods

Contains colored building blocks.

Vampire
sauvva

the player can become a vampire by drinking a potion

My Blocks
Don

Special Blocks

Kill History
LMD

Adds a kill history

HTTPBlocks
56independent

This mod adds a simple HTTP request device for digilines.

Stoneworks
TumeniNodes

Stoneworks simply adds some fun, and cool building options.

Batch Screwdriver
niwla23

With this you can rotate all nodes in a row at once

Noriel Sylvire's Minerals Core Modpack
Noriel_Sylvire

An API for automatically registering recipes, nodes and ore generation.

Meseconometer
DS

Device to meassure time of mesecon signals in globalsteps

Discrete Player API
Hypernoot

A library for games which attaches players to node grid

My Air Wand
Don

A tool to place blocks in mid-air.