In this interview with .net magazine, Flickr founder Caterina Fake likens building an online community to throwing a party:
According to Caterina: "The most difficult part is not the technology but actually getting the people to behave well." When first starting the community the Flickr team were spending nearly 24 hours online greeting each individual user, introducing them to each other and cultivating the community. "After a certain point you can let go and the community will start to maintain itself, explains Caterina. "People will greet each other and introduce their own practices into the social software. It's always underestimated, but early on you need someone in there everyday who is kind of like the host of the party, who introduces everybody and takes their coat.
I recall those early days of Flickr...Stewart and Caterina were everywhere, commenting on everything. A core group of people followed their example and began to do the same, including Heather Champ, who now manages Flickr's community in an official capacity. Matt did a similar thing with MetaFilter too...he spent a lot of time interacting with people on there, taking their coats, and before long others were pitching in.