The Sheep Market is a project by artist/designer
Arron Koblin. Arron enlisted thousands of workers on Amazon's
Mechanical Turk web service and paid them two cents to "draw a sheep facing to the left." The sheep drawings were collected and printed on collectible stamps. The animated process of each sheep's creation may be viewed
here.
UPDATE: Check out
Ten Thousand Cents, another Arron Koblin project.