Forgive me but I will enjoy this exercise … Let me take a stab at explaining Ravelry’s success as domain specific social network site. I do not participate in this group so this is dangerously ungrounded.
Further, I’d be very careful about over valuing a single example, i.e Ravelry. If you want to tease out what makes for a vibrant social network there are lots of vibrant sites which any model has to explain. Some other examples: Howard’s Forums about the telecom industry; Fat Wallet for power shopping/consumers; one of my favorites is Blade and Badger about wet-shaving. There are also ones for every affliction, and ones for every diet fad.
Things about Ravelry…
Group sport two kinds of common cause. Ones which draws them together and ones drives them together.
Common cause/draw: The gravity at Ravelry is their joint problem solving – in this case the problem solving inherent in knitting.
Common cause/drive: What drives them together are those spouses, and others, always suspicious of their partner’s hobbies. They critique the time, the expense, and they tease.
Nature of the talent: There seems to be high correlation between knitting and women in high-tech (the few that are left). Presumably that has been invaluable for Ravelry, but it’s just a hypothesis. Possibly that explains only the overlap between this particular hobby and the internet.
Green space: Craft suffered an interregnum in the late 70s early 80s. It’s back, under the reign of Queen Martha :). But that dry spell enabled a green field for new institutional structures to emerge. I was amused in chatting with people at Etsy. They didn’t even know about the major craft fairs or magazines of the prior era; many of which endure. (Maybe it was the domestic arts, rather than craft that suffered the interregnum?)
Esoteric swag: The stuff required to engage in any enthusiasm is a great catalyst for group forming. This forum at Blade and Badger is a near perfect example of that. Swag gives you something to talk about. It gives you a stream of problems to work through. It enables shopping, sorting, marketplaces, and group buys. Ravelry has a bunch of unique tools that allow members to organize their stash of materials.
Nature of the problems: The problem solving around tools, materials, and patterns has great granularity for the social conversation. This joint problem solving is key to allowing group members to model and act upon one of the cornerstones of good groups – a strong reflex to aid each other.
Common ritual: The literature on groups says they always feature common practice/ritual/jargon – clearly knitting is rich in that.
Signs and Wonders: All groups have a problem with outreach, i.e. how to draw in new members. The evangelical movement has a cliche that advocates “signs and wonders” (i.e. speaking in tongues and miracles make a good draw). Knitting has great outreach because it’s practitioners do it in public and it self starts the conversation.
Riffraff: Like the old National Geographic, the Apalacian Mountain Club, or Google’s mail and voice offerings Ravelry played the exclusivity/scarcity card. You needed an invitation to join.
There are plenty of questions this leaves unaddressed. I’d love to know of other sites where large groups hang out that provide tools for what you might bloodlessly call inventory management. I don’t know what the precursors and competing points of rondevous where. For example were there existing sites that were organizing offline knitting groups. I certainly don’t have any model for how this interacts with the knitting bloggers, who hold a surprisingly large market share in the blogging industry. (“Blogging industry” – HA!)
I’ll leave you with this.