I've rarely seen it work on the Internet. The closest I've seen are some chatrooms, but we know how Omegle turned out.
I find it very ironic that a lot of people have to work for an anarchy. A lot of people who lead these anarchist groups and claim that it's beneficial are fighting with each other too.
It doesn't work in nature either. Animals have leaders. Massive group of cells are controlled by the brain.
I think the hardest thing is that it's just difficult for anarchy to compete with leadership. Leadership tends to turn out better... there's a significant advantage to people who are leading and have a leader. Leadership, management, and administration makes things easier. You just can't handle resources efficiently without one, and it's human nature to make the most use of what they have. Anarchies will either be wiped out by an organized group or the people in the anarchy will gravitate towards organization, just like people are drawn to capitalism.
That's why you only notice these anarchist communities appearing as a result of revolution or other issues where you don't have a leader. And they disappear just as soon as there's a strong enough leader, or when an organized group takes them down.
It's not completely impossible, though. I think one way to do it is to train everyone to be a leader. Instead of having a single, uber-powerful leader, everyone has the right to tell everyone else what to do, which was sort of what the Mongol Horde did.
You train everyone to work and fight as a team, without needing leadership. Everyone learns their own role by instinct. You learn to move in formation without anyone telling you what the formation looks like, and you learn to change formation, just by looking at the situation and what your buddies are doing. You work and get better at work without expecting pay, doing it for the sake of doing it. If someone makes a building, the best man teaches everyone how to do it, and everyone just picks out what tasks they think they can accomplish.
The problem with most anarchies is that they try too hard to be "leaderless" that they avoid guiding each other. Some leadership, some training, some teaching is why those pirate communities lasted so long. There will be criminals, and instead of enforced police, the whole community should be able to punish them.