  Web 2.0 is transforming the internet: Information consumers become
information producers and consumers at the same time. In virtual places like
Facebook, Youtube, discussion boards and weblogs diversificated topics, groups
and issues are propagated and discussed. Today an internet user is a member of
lots of communities at different virtual places. "Real life" group membership
and group behavior has been analyzed in science intensively in the last
decades. Most interestingly, to our knowledge, user roles and behavior have not
been adapted to the modern internet. In this work, we give a short overview of
traditional community roles. We adapt those models and apply them to virtual
online communities. We suggest a community membership life cycle model
describing roles a user can take during his membership in a community. Our
model is systematic and generic; it can be adapted to concrete communities in
the web. The knowledge of a community's life cycle allows influencing the group
structure: Stage transitions can be supported or harmed, e.g. to strengthen the
binding of a user to a site and keep communities alive.
