wikitravel.org is a free worldwide travel guide, and it look pretty nice. One nice thing is that it is created using so called crowd sourcing, just like Open source software or wikipedia. It is an example of many efforts that create high quality outputs by aggregating small outputs of a large group. I read a book called Here Comes Everybody: The Power of Organizing Without Organizations written by Clay Shirky ( Penguin Group 2008) and it discusses many interesting aspects of the power of collective wisdom and it dynamics.
One thing it says is that the reason for organizations to exists is that the communication overhead of arriving at agreements in a group (which needs Cn2 (combination) agreements with peer to peer negotiations that grow very fast with n), and typically organizations reduce the overhead by organization hierarchy or chain of command. However, Internet has changes the communications patterns (e.g. asynchronous messages, broadcasting, posting without knowing recipients) ; therefore, some tasks can be handled without formal organizations. There is lot more interesting stuff there.