I personally would like to see a a horse added to the game. This mob would be more controllable and faster than the ordinary pig.
Also the ocean is missing something. It needs a possible shark mob which attacks users underwater.
Finally i would suggest a cable cart and wire. Say you are on top of a mountain peak and need to travel to a location either below or directly opposite to you. By attaching this long wire to your destination it the suspends the cart on either side and glides when you enter. Also the cart should have the option of a chest or furnace within it.
I like most of your ideas btw.
