MOONBEAM

Non-Moonbeam features:

Blazing Bricks
New building block made of Blaze Powder! Causes damage when mobs walk on top.
Soul Bricks
New building block made of new Soul Bricks! Activates Soul Speed when the player walks on top.
Totem of Undrowning 
New Totem-like item that can save you from drowning. When your oxygen level reaches zero, the Totem of Undrowning saves the day! It refreshes your breath, and gives both Water Breathing and Dolphin's Grace! It is crafted with Lapis Lazuli, a Gold Ingot, and a Heart of the Sea.
Shock

Currently unobtainable Music Disc by MickeySerbia.

Moonbeam Blocks/Items:

Rose Gold
New metal type! Obtained by smithing gold and copper together, used to craft...
Rose Gold Block
Snazzy new metal block, used to craft...
Lunar Summoner
Arguably the most important element of this mod. This block grants access to the Moon dimension, opening up a world moon of possibilities!
Moon Soil
When you set foot on this newfound dimension, you'll discover Moon Soil, a gray material stretching across the barren wasteland. Unfortunately, it's course and rough and it gets everywhere.
Moonstone
If you begin to dig, you'll find Moonstone, a rocky material that may or may not be retextured End Stone.
Dark Moon Soil
Venture to The Dark Side of the Moon (reference intended) and you'll be greeted with menacing Dark Moon Soil, the goth counterpart to regular Moon Soil. Due to the biome's effects, it'll take a while to break.
Dark Moonstone

Beneath Dark Moon Soil, you'll find Dark Moonstone, the equally unpleasant cousin of Dark Moon Soil. It doesn't serve any purpose, but I suppose the builders might enjoy its... darkness.
Whispergrass
In the thicket of the Whisperwood Jungles, you'll most definitely step upon Whispergrass, the peculiar undergrowth that can be found on the moon. Doctors hate her!
Whisperwood
Ah yes, new wood types, everyone's favorite! This variant of log appears in the Whisperwood Jungle, where strange trees grow despite being in the vacuum of space. Doctors hate her, too!

Whisperwood Bulb
A strange fruit sprouts from the bark of Whisperwood trees: Whisperwood Bulbs. These peculiar objects can be brewed into Potions of Eavesdropping, and crafted into Whispering Stew.
Whispering Fern/Flower/Grass
Shooting up from lush Whispergrass comes Whispering Ferns, Flowers, and Grasses, which totally aren't retextured Nether plants.

Moon Rift
If you're brave enough to fight a Wither, you'll obtain a Nether Star, and if your first priority upon obtaining one isn't to create a Beacon, you can sacrifice it to a Lunar Summoner, and tear the fabric of the universe in two to create this Moon Rift. Hop in, and you somehow won't get instantly obliterated by the sudden change in air pressure.

Potion of Eavesdropping

Brewed with a Whisperwood Bulb, this potion lets you see mobs through walls, which is pretty cool.

Lunarite

You can't stay on the moon forever, so if you dig deep enough, you can find Lunarite, a mysterious metal that can be crafted into Lunarite Blocks and...

Earthly Summoner

Spare a diamond and some Lunarite, and you've got yourself an Earthly Summoner, your one ticket back to the Overworld. Just make sure you brought a spare Nether Star, because you're going to need it if you want to activate the portal...
Moon Acid
In the Moon's hostile Acid Lakes, you can find Moon Acid, a deadly green liquid that will most certainly cause any nearby dermatologists to faint.

Night Vision Goggles

Using Amethyst Crystals and any type of helmet, you can make Night Vision Goggles, a surefire way to traverse the Dark Side biome without having to lose all your vision.

Porcelain

Crafting item, obtained by stacking two clay in the crafting grid.
China

Placeable bowl-type block, crafted with 3 Porcelain. Available in all colors, each with different patterns.

China Blocks

Decorative blocks, crafted with 4 of each type of china. Available in all colors, each with different designs. Includes 1.18 and 1.19 mobs!

Monolith Stone

A dark indestructible stone found on the moon.

Monolith

The Moon equivalent of a Respawn Anchor. Works in all dimensions (I think)

Wakegrass

Within the rolling hills of the Wakewood Jungles, you run through Wakegrass, the blue brother of Whispergrass.

Moonbeam Biomes/Structures:

Lunar Wasteland

The moon is gray, obviously, so this biome is, too. Gray dirt, gray stone, gray everything. It's quite boring, really.

The Dark Side

Without the cheesy Pink Floyd references, the Dark Side is actually a pretty mundane biome. The color palette is just as unique as the Lunar Wasteland.
Whisperwood Jungle
Despite a monotonous color scheme that's starting to become a pattern in this mod, the Whisperwood Jungle contains many strange types of fauna that Earth could support, but probably shouldn't.
Acid Lake

Past the Basalt shores, you'll find the menacing Acid Lakes, large seas of lime green liquid that will definitely scar you, mentally and physically.

Wakewood Jungle

Another variant of extraterrestrial flora, Wakewood Trees inhabit a baby blue ecosystem of plants being pulled upwards due to the irregular gravity of the Moon.

Monoliths

New structures to help set your spawn point on the Moon.

Asteroids

New structures that can contain Iron, Copper, or Gold. Used for finding resources on the Moon.

Moonbeam Advancements:

We're Going On A Trip - Place a Lunar Summoner

Mumbo, Is The Moon Big? - Enter the Moon dimension

Pink Floyd - Visit a Dark Side biome

A Thousand Voices - Visit a Whisperwood Jungle

Mad Sus - Drink an Eavesdropping potion

Weird Science - Obtain Lunarite
Pale Blue Dot - Place an Earthly Summoner

Hot Potato - Place a Blazing block
Subnautical - Have your life saved by a Totem of Undrowning

Arborist - Achievement for obtaining all vanilla wood types

Electrified - Achievement for obtaining new Music Disc "Shock"

UPDATE 1.1.0: THE COLORFUL CHINA UPDATE

New Blocks/Items:

Porcelain - New item, obtained by stacking two clay in the crafting grid
China - New placeable bowl-type block, crafted with 3 Porcelain. Available in all colors, each with different patterns.

China Blocks - New decorative blocks, crafted with 4 of each type of china. Available in all colors, each with different designs. Includes 1.18 and 1.19 mobs!

UPDATE 1.2.0: THE ARMOR & ARBOR UPDATE

New Non-Moonbeam Features:

Shock - New music disc, currently unobtainable. Music by MickeySerbia.

New Blocks/Items:

Monolith Stone - A dark indestructible stone found on the moon.

Monolith - The Moon equivalent of a Respawn Anchor. Works in all dimensions. (I think)

Wakegrass - Within the rolling hills of the Wakewood Jungles, you run through Wakegrass, the blue brother of Whispergrass.

Traveler's Helmet - Coonskin cap, lets you see the light level, time of day, coordinates, and a notification letting you know if mobs can spawn.

Sorcerer's Cloak - Gives you an effect nullifying negative potion effects at the cost of levels.

Hunter's Leggings - Lets you know if mobs are nearby.

Architect's Boots - Places the block in your main-hand under you. Useful for building large structures.

New Biomes/Structures:

Wakewood Jungle - Another variant of extraterrestrial flora, Wakewood Trees inhabit a baby blue ecosystem of plants being pulled upwards due to the irregular gravity of the Moon.

Monoliths - New structures to help set your spawn point on the Moon.

Asteroids - New structures that can contain Iron, Copper, or Gold. Used for finding resources on the Moon.

New Advancements:

Arborist - Achievement for obtaining all vanilla wood types

Electrified - Achievement for obtaining new Music Disc "Shock"