From Social Patterns

Perhaps the most immediate interface technique for keeping the current user company is to show them who else is currently logged into the site. While they may be physically remote, in a sense they are sharing the user’s current experience by co-browsing the same site.

RateMyDrawings.com indicates who else is logged into the site and gives you a way to select that person to see their contributions.

Similarly, Facebook now shows you which of your “friends” are currently online.

Once Facebook launched its own instant messenger service their Online Friends feature came full circle, essentially replicating the fundamental “availability” presence pattern

• Keep Company
  • Signs of Life
  • User Gallery
  • Who’s Here Now?
  • Ambient Intimacy