Wikipedia is simply amazing. Google some even mildly obscure term, and Wikipedia will almost definitely be in the top ten, if not number one. What makes it work is the fact that there is nobody controlling how it works. You can go on there and add anything you want, even deliberate lies, yet it still works.
It's predecessor, Nupedia, was a more or less traditional approach. Though anybody could submit an article, it had a formal peer-review process that made sure that any article submitted had cleared a high hurdle of accuracy, accountablility before it ever saw the light of the internet. It based its credibility and level of expertise on these processes.
Nupedia's successor, Wikipedia, threw out all the formality of peer review along with any hint of accountability. It was not only a popular success, but it acheived a level of credibility and expertise that, if not quite as firm as traditional encyclopedias, was good enough for most purposes. And it did it with an accessibility that absolutely put to shame that of any traditional scholarly sources.
Though there was no one guiding it, no-one and no process assuring credibility and expertise, these qualities emerged from the chaos of allowing anyone to add anything they wanted, subject only to the editing of the next guy who may or may not correct any inaccuracies or outright lies. It's an example of spontaneous order, which I mentioned in my first Advancement Tech article.
Without centralized control, order emerged from the chaos. Without authority, it became authoritative. Without accountability, it became trusted. This is an inspiration to those of us who see order in markets and private law that can emerge from the chaos of everybody ruthlessly pursing their own self-interest.