Wikipedia Editors:

Note the virtuous circle at work here: because enough people thought of using Wikipedia as a coordinating resource, it became one, and because it became one, more people learned to think of it as a coordinating resource.

Excerpt from Here Comes Everybody by Clay Shirky

http://www.shirky.com/

      Termites:

When they start to build a nest, termites modify their local environment by making little mud balls and placing them on the substrate; each mud ball is impregnated with a minute quantity of a particular pheromone. Termites deposit their mud balls probabilisticly, initially a random. However, the probability of depositing a mud ball at a given location increases with the sensed presence of other mud balls and the sensed concentration of pheromone. The first few random placements increase the other termites probability of putting their loads at the same place. By this blind and random game little columns are formed; the pheromone drifting across from neighboring columns causes the tops of the columns to be built with a bias towards the neighbouring columns, and eventually the tops meet to form arches2, the basic building units.

Excerpt from Coordination without Communication by Stan Franklin

http://www.msci.memphis.edu/~franklin/coord.html

Who would have thought? Go Wikipedia editors!