Admidio is a free online membership management, optimized for clubs, groups and organizations. It consists of classical management members from a variety of modules that can be installed and adjusted to a new or existing website. Registered users have your website by Admidio including access to predefined and user-configurable membership lists, people profiles and an Agenda. In addition, members may be pooled in groups are assigned properties and search for it.
More information on : http://www.admidio.org