I'm going to describe over 30 ideas of mine! Hope you like them :)
1. Quiver
- The old fashioned quiver that can be used as a portable storage only for arrows.

2. Fish
- A new water mob. The fish. The fish can be obtained by fishing normally in Minecraft, but you can see the fish. Also, if you kill the fish with a weapon ore anything, I will only drop 3 - 5 XP Orbs.

3. Different colored fence
- Spruce wood fence, Default Oak wood fence, Birch Wood fence and Jungle wood fence. This will be cool if it is added into Minecraft.

4. Enhanced pistons
- Pistons, that can be crafted with a normal piston and 8 redstone. The enhanced piston will push Items / Sand / NPCs / Players into the air when powered by redstone.

5. Rugs / carpet
- Rugs or Carpets, crafted with 3 colored wool and high 2 pixels from the ground. Used for decoration.

6. Torch upgrade
- When held, torches should emit light as well when they are thrown.

7. Custom NPCs
- NPCs, that can only be spawned from an egg. You can choose their names above the their heads and you can put them a custom skin. Good for adventure maps. You can as well customize the message they say when you right-click them and the item (optional) that they will give you. You can modify the item the hold as well.

8. The "Separator" block
- A block, that opens a GUI, where you can put an item (for example a chest) and it will separate it to the items / blocks you used to craft it ( 8 wooden planks for the chest, 8 cobble for furnace, 5 iron for and iron helmet etc.)

9. Glass with frame
- A new glass, crafted with normal glass with stone surrounding it. It's like normal glass, but with a nice stone frame. When two framed glass blocks put next to each other, the frame connects.

10. Colored Beds
- Beds with all the wool colors. For example, if you used blue wool to craft the bed, when you place it it will be blue color! Works with all other colors.

11. Adventure Mode
- From the world creation menu, from the gamemodes there are Creative, Survival, Hardcore and Adventure. Just like the regular adventure mode in Minecraft, but with more features. Villages are 20% more common. In the caves, there are Miner's shelters with chest with torches, pickaxes and other materials.

12. Cloud upgrade
- Clouds are made out of blocks, that you can mine. Used for decoration. The blocks (clouds) still move in the air, but can be mined.

13. Clock upgrade
- Clocks to be able to be placed on the wall without using an item frame. The first time I played Minecraft I thought clocks will be able to be placed. That will be awesome.

14. Mirrored glass
- Special crafted glass, witch acts like a mirror when placed.

15. Golden Bread
- Crafted with a bread and 8 gold nuggets. Restores 4 hunger (2 chicken nuggets) and give Speed Boost II for 10 seconds.

16. Apple Pie
- Like pumpkin pie but instead of pumpkin, it's crafted with an apple.

17. Redstone Arrow
- Crafted with a regular arrow and a piece of redstone. Deals normal arrow damage, but also poweres redstone wire if it touches it.

18. Glowstone arrow
- Same crafting as Redstone Arrow, but instead of redstone there's glowstone dust. This arrow grows when shot.

19. Sling
- Crafted with string and leather. Shoots stone blocks. Hold RMB (right mouse button) to charge and release RMB to shoot. Has 20 durability (20 shots) and it deals from 2 (minimum charge) to 5 (maxumim charge) hearts.

20. Cyan Flower
- This flower is already in the Pocket Edition. It will be nice if they add it into the PC version. 1 cyan flower = 1 cyan dye'

21. Jungle Armor
- Crafted with leaves, vines and iron ingots. When stepping on grass or leaves you are invisible. Each armor piece is strong as chain armor. Has 350 durability.

22. Apple upgrade
- When on leaves on trees, apples to be seen as items.

23. Chocolate Milk
- Crafted with milk, sugar and cocoa beans. Drinkable. Restores 7 health (3.5 hearts) and 4 hunger.

24. Craftable sponge
- Sponge can be crafted. Sponge is awesome for decoration!

25. Colored torches
- Torch and the dye on top of it to make it colored. Glows with the color you crafted it with. Terraria kinda inspired me for that ;)

26. FPS Smother
- A new option in video settings called "Smooth FPS". That will boost your FPS. Good for slow PCs (like my PC :()

27. Sky Dungeon
- When you enter a cloud, there's a 5-10% chance to be teleported into the Sky Dimension. There you can find the sky dungeon. It is a big, 4-floored dungeon with loot and wither skeletons guarding the dungeon.

28. Spawner Upgrade
- When you break a Monster Spawner it drops an "Empty Monster Spawner". When you surround the empty spawner with the specified mob drop (for example rotten flesh for zombies) and put a diamond on the top, you get the spawner for the mob you chose

29. "Island" biome
- In the ocean biomes, there can be found the new Island biome. It's not just a regular island like in Minecraft, island with trees! Palm trees! Look next idea for more info.

30. Palm trees
- Palm trees only spawn in island biomes, but when you get the sapling, you can grow them anywhere you like. You can craft Palm wood and palm wood planks! The color is brown-grey and the leaves are palm leaves.

31. Fox mob
- A new mob, the fox. Can be found in forest biomes and drops leather and 5 XP Orbs.

32. Obsidian Shield
- As the title says, the shield is made out of obsidian. When you are holding the shield, you take 0 damage. It's durability is 100 and needs 7 obsidian to craft.

33. Painting upgrade
- When you place a painting, it opens a GUI, where you can select the painting that you can place there. Click on a painting and you will place it. Easier that placing and braking until you get the painting you like.

34. Block of Redstone
- Crafted like any other block of material (diamond block, gold block ect.). Used for redstone storage and decoration. Has a texture like diamond block, but red.

35. Wither Bow
- A new bow, that is crafted like a normal bow, but instead of sticks, put obsidian and a nether star in the center. As well, wither skeletons have a 0.5% chance of dropping that bow. It has 5000 durability. Shoots arrows 150% more accurate than the regular bow. Deals from 18 to 25 damage (depends on how much it's charged). It deals the damage and gives the mob it hits the "Wither II" effect. If it's hold more than 5 seconds, it is supercharged. Supercharged wither bow deals 35 damage. This bow is awesome, but you need to kill the wither to craft it, so it's not that easy to get it.

36. Backpack
- Crafted with 8 leather. Equip this on your chestplate armor slot and you will get 27 more inventory space. When the backpack is removed (unquipped), it saves the items. But if it's thrown in lava or fire, you loose all the items in it.

I know they are too much, but that's a good contest entry :D