Two online groups which I've followed off and on for some time are the newsgroup, soc.religion.quaker, and a listserv group called WWWW, (Wild Wolf Women on the Web). The first is, as expected, an information-oriented group devoted to disseminating information about the Society of Friends, a.k.a. Quakers. The second was begun in response to the book, "Women Who Run with the Wolves," by C.P. Estes. It is a women's (but men are not excluded) group for discussion, support, and socializing.
Establishing identity in these groups follows some patterns. In the Quaker group, people's identity is usually not masked. They act as real-life individuals, sending e-mail to a group. People usually atttach their real names to their e-mail messages. More subtle indications of identity, e.g., personality, political and religious affiliation, are displayed in the signature files which are used by a large percentage of the group. Some examples from the Quaker group (these are exact quotes):Suport the Campaign for the ReIntroduction of the Second Person Plural Pronoun... "There is one, even Christ Jesus, who can speak to thy condition." Freedom is the primary cause of Peace, Love, Truth and Justice. Life is too short to belittle "This bluegreen ball in blackspace/ Filled with beauty even now/ battered and abused and lovely."
In WWWW, there are several aspects to identity. To make the picture clear, it is important to know the social metaphor upon which this group is based. The wild, elemental archetype of woman discussed in Estes' book is taken as a theme. They portray themselves as Wolf-Women and their wolf-den is the metaphor of place here. Members are referred to as pack-mates. It works wonderfully well -- combining many of the mind-picture effects of a MUD with a mailing list interchange.
When new members join the group, they are encouraged to pick a wolf-name. Most do. And often, they are as revealing about identity (psychological identity, their geographical or cultural identity, etc.) as the signature texts of the newsgroup. Some examples: Laughing Wolf, DesertWindWolf, ShyWolf, Swampy, CopWolf. Identity is also part of the discussion. People talk about themselves in great detail, their innermost feelings, etc. This group feels like a safe area. There are many language cues here, and people are very expressive of support for one another. There is a story on their web page which I will only link here, since it's too long to quote, but reading it will give you a vivid picture of the interactions of various "wolves" in the "den" and the way that identity and relationships are expressed: http://www.wildwolfwomen.com/mirror.html. The wolf den mentioned in the story is, of course, the WWWW group.
Conversation: The Quakers seem to be quite consistent in staying within threads in their postings. There is an assumption that the format of this group is a forum for answering questions about the Quaker religion. So most threads/discussions/conversations revolve around a question, then a discussion thread evolving around the answer. These discussions can get very involved, and often spin off other discussions. The mechanism for "threading" is pretty well established as stating the thread in the subject line and quoting the relevant portions from the previous person's message, then continuing. Often this leads to deeply nested quotes, which can sometimes be more confusing than helpful.
In the WWWW group, members also try to stick to threads, which are referenced in the subject line of the message. However, writers often reply to one thread in the subject line, and actually discuss several topics in their message. Many members will submit a daily message that includes greetings to a number of "wolfies" who have posted that day or the previous day, and reply to the several threads that are going on currently. The most common mechanism for referring to specific conversation is "snipping", quoting selected text. Confusion and the overwhelming number of messages finally led to a filter mechanism that filters messages for a few very popular topics only to those members who have specifically subscribed to that topic. Whatever organization is imposed, it is still clear that a cocktail party type of conversation is continuous here. People can be having a serious discussion but there are constant side-conversations, interrupting to send greetings to someone coming by, asking how the new job is going, etc.
Social structure: Both groups mirror their origins in real life. Quaker meetings do not have a minister or any one person who speaks for the group (with the exception of administrative affairs). They strive to be non-hierachical, and this shows itself in the group. There are some members who speak more often than others, but they clearly do not assume any leadership. I witnessed one interesting incident: a very disruptive spammer who claimed to be a "Christian Minister" would not stop sending very insulting messages to members of the group. Those singled out by the spammer were often the most kindly, gentle members of the group. They responded with pacifist, patient, logical (in argument) messages. Finally, however the group's patience was tried enough that they began a discussion of actually trying to filter out spam with various filtering software. The matter was to be decided by vote. I stopped reading the group during the interval when voting was to occur, so unfortunately, I don't know the outcome. (This was over a year ago.)
Within the context of a close-knit wolf-den group, the social metaphors range from informal social encounters like cocktail parties, to the intimate get-togethers of women exploring deep and personal issues. People in the group definitely take on roles. (See the linked article above for many examples.) There are two co-owners of the list, who are the technical resources and gate-keepers. The list is currently closed. It became too big to be manageable over a year ago, so now new members are only admitted when there is an opening created by someone leaving. There is the peace-maker, who tries to iron out "misunderstandings", there is the "enforcer", who chastises people for the "faults" of being too hard on themselves, not giving themselves enough credit, apologizing too much, etc. If there are any sub-goups to speak of, they tend to form based on longevity in the list. The old-timers are definitely a group that the rest of the members look up to. In this group, history matters, and the old-timers are the ones who keep up the stories.