This plugin restrict access to Joomla site to registered users only to read the full post for joomla 1.5, When a guest tries to access any Joomla content, they are redirected to the login page.
Download RegisteredOnly: Register Read Full Joomla Plugin
http://www.box.net/shared/i34f1d06f3
http://rapidshare.com/files/389630869/plg_registeredOnly-0.2.tar.gz
http://joomlacode.org/gf/project/registeredonly/frs/
