Translucent/Frosted glass, maybe Glass + Sand? Ice now craftable/harvestable and used as a transparent block. More transparent/translucent blocks in general
Glass + Glowdust (+ iron ingot) = Lantern x4, can be hung from ceiling, greater luminosity and radius than torches. Perhaps use dyes to have different tinted lights?
Sandstone Weapons (same durability as wood) for those who start in desert biomes
[Sandstone in furnace makes Porcelain/Marble? Or craft Stone + Slimeball to make some sort of shiny stone.
Wood + Slimeball (or resin from 4 logs -> 1 tree sap) makes Varnished Wood, same texture but shiny
Squid Ink + Wood = Stained wood, darker shade, maybe Wood + Red Dye = Mahogany?
Using Bonemeal on dirt makes grass grow instantly. Using bonemeal on tree/leaf blocks will cause 1 leaf block to grow in all adjacent empty spaces to that block, up to a certain limit.
Shrubs can be planted via a new sapling, and grow into 3x3x3 or larger blocks of leaves. They can then be carved into hedge mazes or topiaries.
Sleeping in a bed during the day instantly fastforwards to sunset
Fishing can randomly give you empty buckets and pieces of armor.
Trees/logs submerged in water will eventually become Petrified Logs, which can only be harvested with a diamond axe. Petrified Logs can be crafted into Petrified Wood, which is not flammable and has a higher blast resistance. Tools made from Petrified Wood have the speed of gold and the durability of stone tools
You can also use Petrified Wood to make Petrified sticks and then turn those into an Ancient Fishing Rod. Ancient Fishing Rods can be used to catch larger fish (restore more health), and have a small chance of fishing up a Kraken (see below, boss type monster)
Clay can be made by placing gravel near water (not my idea). Perhaps some way to get clay by crafting gravel + water, or mud (can fire into terra cotta bricks) by using dirt + water?
Silver Ore can now be found, about as common as Lapis Lazuli. Silver tools have slightly higher durability than stone.
Silver Ingot at the center of 8 sticks = Mirror, can be hung like a painting and can reflect light
Craftable shields. Silver shields can automatically reflect ghost fireballs, but lose durability like regular armor.
Gold and Silver Ingots can be crafted into coins (1 ingot = 4 coins). Differing amounts of Gold/Silver coins can be traded to rare traveling NPC merchants for rarer materials.
Glowstone more common in the Nether. Either Glowstone gives 4-6 glowdust per stone, or it only requires 4 dust to make 1 block. Add passive glow worms (can climb walls like spiders) to the Nether that can drop dust as well.
Nether Portals can be made out of 5x5 Obsidian as well as 4x5
More painting sizes, such as 3x2, 3x3, 5x4 and 5x5. Paintings can be right clicked once placed to cycle through all paintings of the same size.
Two chests stacked vertically on a crafting table (with white dye?) makes a refrigerator, which can be used to store food (no other difference with a double chest). Other craftable furniture like armoires or wardrobes, which look different but function the same as chests.
Craftable Oven which uses fuel twice as fast, but will cook all food (only works on meat/fish/etc) in a 4x4 area simultaneously.
Crafting a bookshelf with a chest as the center space (instead of a 3rd book) will create a secret Book Safe, looks almost identical to bookshelves but holds items. Bookshelves can now be broken and retrieved without losing the block.
Way to display items, such as a mannequin to show armor. Perhaps display cases (glass on top, wood on the sides, red wool on the bottom) which can show off items (the small item icons). Perhaps shelves that can used to easily display/store item icons.
Chairs and tables, maybe even couches (make them sectional so you can craft a left end/right end/corner piece and fill in the rest to make larger ones). Benches or desks too
Craftable faucet (wood + iron ingot + bucket of water) that can used as an infinite water source (right click with empty bucket to fill)
Wool can be crafted into cloth armor, very little defense value but looks different. Can use colored wool to make colored clothes, also special recipes using mixed colors to make a few special items like tuxedos or creeper costumes. Creeper costumes prevent you from being aggro'd by creepers unless you attack them first
Either allow wool to be downcrafted into string, or add a loom furnishing that can spin wool into string or can be used in making clothes.
Larger beds (3x3 king size, 2x2 queen size) made by crafting beds next to each other
Waterwheel item that can be placed in flowing water to permanently power furnaces, at half smelting speed. Or, an item that can be placed atop lava to accomplish the same thing with geothermal power. Can link item to furnace with redstone wire.
9 coal -> 1 Coal Brick, 9 coal bricks -> 1 carbon brick, 9 carbon bricks = 1 diamond. Perhaps use carbon bricks to strengthen tools somehow?
Diamond + 8 redstone = Magic Stone. Crafting a Magic diamond + stick + gold ingot = Magic Wand, can be used to shoot your own ghast fireballs (consumes 1 book per use)
Magic Stones can also be made into an Enchanted Pickaxe. Same durability as diamond, but can harvest Obsidian in half the time.
8 Magic Stones can be made into a Magic Chest. Items placed in a Magic Chest can be retrieved from any other Magic Chest in the world.
Arrows can be made with iron ingots instead of flint. Iron arrows deal twice as much damage. Skeletons still only drop regular arrows, meaning you can only obtain Iron arrows through crafting.
Ability to Brand cattle (brand = iron ingot + torch) to make them follow you (right click to have them start/stop moving) and not despawn. Can also herd sheep (sheepherder cane made from sticks in a cane shape maybe?) and pigs.
4 sticks can be crafted into wheels, and combined with a chest to make an Ox Cart, which can be attached to a branded (tamed) cow. The cow will follow you making it another form of mobile storage, except it only works on flat areas since attaching the cart prevents the cow from jumping. If the cow dies the cart turns back into an item and all items in the chest are dumped onto the ground.
Bottles made from glass (3 glass blocks -> 3 bottles) which can be filled with milk and give back an empty bottle when used (2 uses per bottle, restores 2-3 hearts). Like mushroom stew, using a drink gives you back an empty bottle.
Cocoa beans can be planted to grow more. Bottles can also be filled with milk + cocoa beans to make Chocolate Milk, which restores no hearts but increases walking and mining speed by 25% for 15 minutes.
Rain makes flowers and pumpkins spread out randomly from a source flower much like grass. Mushrooms can randomly spawn/spread on stone surfaces in low light. Rain also increases the rate at which grass grows.
Rain can also cause apples to grow randomly on trees (not spruce/birch). Apples can be fed to pigs to increase the amount of pork you receive from them when killed. Apples fed to tamed sheep will instantly regrow their wool.
Boss type monsters (super creeper, dragon, kraken, etc) that drop a dungeon treasure chest when killed. Kraken listed above, super creeper spawns by defeating a bunch of creepers in a row with your bare hands without any explosions, etc.
Cobblestone + seeds (or green dye) = Moss Stone
Mining smooth stone now gives smooth stone, making cobblestone requires simply crafting (1:1 ratio) the smooth stone. Can now make steps out of smooth stone.
Slabs for diamond, lapis, iron, and gold. Once made into slabs they can not be re-crafted into ingots. Wool slabs too?
Iron helmet + glowstone = Mining helmet, personal light source (no armor value, but doesn't break)
Iron helmet + glass = Diving helmet, gives 3x air supply and improves visibility underwater
Slimeball x9 = Slime Block, 4 slime blocks -> Slime Boots, can be used to jump 2 blocks instead of 1. Low durability
Wood armor that affords greater protection as leather, but increased damage from fire/lava and will catch fire if hit by creeper/ghast explosion
Minecarts can be linked together to allow them to move more easily, left clicking a powered minecart will make it change directions and it can be loaded with fuel en route to allow easy fast travel.
Boats can also be retrieved now, and don't break when you hit things.
2 gold ingots can be crafted into a Key. When right clicking on a regular chest with a Key, that chest becomes a Locked Chest and cannot be opened or broken by other players. The only way to open it is to right click on it again with the same key. If the original key is lost/destroyed the locked chest reverts to a regular chest.
8 iron ingots with a hole in the center = Safe. Works just like a regular chest (can be locked with a key as well) but cannot be placed side by side to double capacity. Safes cannot be destroyed by explosions.
Redstone x9 -> Redstone block, can be placed or used for storage. (conducts electricity like redstone wire?)
Water can be placed in the nether but will eventually turn into poison. Stepping in poison will gradually reduce your health until you eat food. Poison can be gathered into buckets and used in mob traps, or applied to swords/bows to let you inflict poison on mobs. Trees planted near poison will eventually turn black.
Add in Gates (2x2), Tall Doors (3x1), and Great Doors (3x2).
Grapple/Hookshot (also not my idea)