Sheep are the prime suppliers of wool and have been ever since they muscled out their Competition, the woolly mammoth, however they are currently on strike and will be for the foreseeable future.
To be honest, sheep are a very boring sort of animal. This is why they are so good at helping to put people to sleep. As the Australians say "You never have any trouble sleeping with a sheep."
Sheep were greatly revolutionized upon the invention of the Sheep Pod. Sheep barely escaped extinction in the Hundred Year Sheep Purge, but were saved as a species by the Dutch Underground Railroad from the slaughter which decimated the followers of sheep-controlled Woolco.
Wool, which keeps sheep cute and cuddly, was invented by Albert Einstein.
Sheep are actually a collective (or hive) creature which is why the singular and plural forms are the same.
There are also vampire sheep.
See also Ducksheep [про овцеуток мне тоже очень понравилось]
Source: SHEEP, according to UncyclopediA