Theresa Nielsen Hayden, cofounder of the website Making Light, and community manager of Boing Boing, uses the term sitegeist to define the atmosphere of a website with a vibrant community:

“When you really get a community growing up around [a website], it is so much more than the blog entries themselves or the content itself,” she says. “It’s that gestalt of people talking back and forth to each other, the expectations they have of the website, and the sense they have of it.”

She’s coined the term “site-geist” to describe that environment: “Even people who aren’t really conscious of it will still have it, and they’ll assimilate the implications of even small changes to the site rapidly. They do it without thinking about it. One of the interesting things of moderating a community is being mindful of that.”

(Via Future Changes)