Improved Chicken Farm Tutorial
This chicken farm will collect the eggs automatically, and put them in a chest for you, so you don't have to keep going back every 5 minutes.
What you will need
In addition to basic building materials (wood, stone, whatever) you will need a bucket (made from 3 iron) and a hopper (made from 5 iron and a chest), one more chest, and a wooden sign.
Building instructions
Build a 5x5 platform with a hole in the centre.
Place a sign inside the hole (you can write anything you like on it!)
Build up a wall all around the edge
Get 4 buckets of water and pour one in each corner.
The water will flow towards the centre, but it will not go through because of the sign you placed there.
Build up the walls a little higher. A half-slab is tall enough so that you will be able to climb out if you fall in, but the chickens won't.
Place a chest on the ground underneath the central hole.
Place a hopper on top of the chest (to do this you must sneak (hold down SHIFT) whilst placing the hopper, otherwise you will just open the chest).
Now fill up your farm with chickens, by throwing eggs or luring them in with seeds.
The chickens will float about in the water laying eggs, which will be collected into the chest underneath.
Tips
Once you get to the stage of the game where you can make potions, a splash potion of harming is a great way to kill lots of chickens at once.