Community Builder is a very popular Joomla! Extension.
Check out these video tutorials, provided by JoomlaTutorials.com!
http://www.joomlatutorials.com/joomla_tutorials/community_builder/configuration/details.html http://www.joomlatutorials.com/joomla_tutorials/community_builder/fields/details.html
http://www.joomlatutorials.com/joomla_tutorials/community_builder/tabs/details.html
http://www.joomlatutorials.com/joomla_tutorials/community_builder/plugins/details.html
http://www.joomlatutorials.com/joomla_tutorials/community_builder/lists/details.html
