1.- Less lag!

2.- The higher the difficulty you are the bigger a creeper explosion would be

3.- Being able of sprinting while flying, simply you will go faster

4.- You can see the fishes

5.- Squids would spawn more rarely ( so when you make a pool squids wouldn't spawn on it :| )

6.- Killing the Wither will give you more experience

7.- Overpowered rail, this one makes the minecart go 2x faster than the normal powered rail :)

8.- If you put a bow with infinity and an arrow on a dispenser the dispenser will shoot infinitely until the bows breaks

9.- If you attack the Iron Golem it will attack you, the same with the Snow Golem!

10.- Fire Golems! to make it simply do the same things as the snow golem but replace the snow with netherrack and the pumkpin needs to be a Jack o' Latern, this will also attack you if you attack it, also they will spawn on the Nether angry :o, yeah they will leave a fire spread

11.- New command: /gamerule doPlantsGrowning false, this will make plants don't grow including the saplings (exception if using bonemeal)

12.- Another command: /gamerule do grassSpread false, this will make dirt do not convert into grass when there is grass near (the same with mycelium)

13.- The /back command on bukkit servers would be on normal Minecraft, even on singleplayer!

14.- Sand Golem, this one is the same as Snow Golems instead these fire "Sandballs", this "Sandballs" are craftable putting 1 sand on the crafting table, these will only damage Endermen but not the Enderdragon, thespecialthing about Sand Golems is that they won't die on Water, at Desert Biomes and Jungle Biomes, instead they will die at Snow Biomes.

15.- Green Apples,they are rarer than normal Apples, also it will feed you more, and the also you can make the golden(butter) green apple the same way as normal Golden(butter) apples, just that this ones will make the Regeneration be a little bit more time.

16.- A new potion: you must put a invisibility potion in a brewing stand you also put a green golden(butter) apple and then you put a fermented spider eye, this potion will let you see players who use the invincibility potion, pretty useful uh?

17.- ModLoader or ModApi and Forge will now be installed on Minecraft!

18.- Sticky Arrows! This one is craftable using an arrow and up using a Slimeball, this will make mobs go slower just like they had the Slowness potion when you shoot them.

19.- Slimeblock! Crafted using 4 Slimeballs, you will go slower than being on Soul Sand on Ice, and there won't be fall damage.

20.- Iron Bars Blocks! Crafted using 4 Iron Bars, with this you can also make Iron Bars Block Slab and Iron Bars Block Stairs!

21.- Poison enchant! You simply enchant a bow or sword and there will be an enchant of poison which gives poison for the time of the level it is (example: level 4 poison= 4 seconds of poison, level 1 poison= 1 second of poison)

I wait you like my ideas :D