I just came across Mr. John Suler, Ph.D. who is Professor of Psychology at the Rider University – and found a lot of interesting articles published on the dynamics of online communities, or internet psychology in general.

The experience created by computers and computer networks can in many ways be understood as a psychological "space." When they power up their computers, launch a program, write e-mail, or log on to their online service, users often feel – consciously or subconsciously – that they are entering a "place" or "space" that is filled with a wide array of meanings and purposes.
[...]

On an even deeper psychological level, users often describe how their computer is an extension of their mind and personality – a "space" that reflects their tastes, attitudes, and interests.

from the Psychology of Cyberspace

• Level of Dissociation and Integration: The multiple aspects of one's identity may be dissociated, enhanced, or integrated online.
• Positive and Negative Valence : Negative aspects of identity can be acted out or worked through. Positive aspects can be expressed and developed.
• Level of Fantasy or Reality: One's online identity can be real-to-life, imaginary, or hidden.
• Level of Conscious Awareness and Control: People differ in how much their unconscious needs and emotions surface in their online identities.
• The Media Chosen: Different communication channels express different aspects of identity.

from The Psychology of the Individual in Cyberspace

and most interesting : Social psychology of online groups

Groups ranging in size from a few people to thousands and millions within a “community” are forming within cyberspace. Many of the classic social-psychological principles of group dynamics can be applied in understanding and improving the functioning of these groups – such as issues concerning leadership, communication patterns, group boundaries, cohesion, alliances and subgroupings.

[...]

Every list (community) seems to go through the same cycle:

1. Initial enthusiasm
2. Evangelism

3. Growth

4. Community

5. Discomfort with diversity

then the interesting final stage

6a. Smug complacency and stagnation – the purists flame everyone who asks an 'old' question or responds with humor to a serious post; newbies are rebuffed; traffic drops to a doze-producing level of a few minor issues; … etc.etc.
OR

6b. Maturity – a few people quit in a huff; the rest of the participants stay near stage 4, with stage 5 popping up briefly every few weeks;

from Group Dynamics in Cyberspace

Another REALLY old article from Wired – back from 1994 – Nine Principles for Making Virtual Communities Work is a good base read on the topic of online communities as well…