Minecraft wiki entry for 2010_Indie_of_the_Year_Awards, associated text: Pigs: drop porkchops upon death and can be ridden using a saddle and holding a carrot on a stick.
Cows: drop beef upon death and can be milked using a bucket.
Sheep: drop mutton and 1 wool upon death and can be sheared to produce 1–3 wools.
Chickens: drop chicken and feathers upon death and lay eggs.
Horses: drop leather upon death and can be ridden using a saddle, traveling much faster than pigs.
Rabbits: drop rabbit meat, hide and its foot, a brewing item.
Bats: ambient mobs that fly around caves.
Fish: passive ambient mobs that drop diverse items such as food or bones.