It seems to me that healthy communities have two main elements:
1) constant, local activity: people meet regularly on a very local level, in their city, their area. The activity is organized by members. Thanks to this element the community is a constant value in the people's lives and it allows them to build meaningful relationships and build up real trust to people within that community even beyond their local community.
2) emotional peaks: from time to time a special event happens, something which is very exciting, where members meet totally new members, where they expand their horizon, but also where they grasp the community as a whole. They leave these peak experiences totally empowered and happy to be part of such an incredible group of peers. These can be global events, maybe competitions, incubation programs, retreats.
With only one of these elements, something essential would be missing:
Many large conferences claim to provide a community. However, fact is that most people feel this sense of belonging only during a very limited time when they are phyisically at the conference and shortly after. Even though the conferences themselves are life-changing moments and no doubt emotional peak experiences, the trust and connectedness between these conferences is quite small.
On the other hand, local communities run the danger of running out of exciting events. At some point, people know each other and the buzz moves on. If a community is "only" local, the feeling of global importance is missing.
In an ideal world, these two elements can be combined by a third one: editorial content and technology, that connects community members globally and prolongs the effects before and after any activity (with invitations, previews, reviews, stories from the network, etc).
Update: on a local level, all members should really know each other, have close bonding experiences. You can combine this then with meeting "strangers" on a regional and global level. Ideally, the trust that members generated on a local level will last even with people they don't know. Inspired by this.
