OjAccess is a simple content plugin for joomla 1.5, it allows guest or user etc... can see certain portions of a content item to any Joomla! group. Fully configurable to allow compound and also negative conditions. And very easy to use this

{ojaccess guest}shows only to guest users{/ojaccess}
{ojaccess !guest}shows to all users who are not a guest{/ojaccess}
{ojaccess registered}shows to all users who are registered{/ojaccess}
{ojaccess guest,!editor}shows to all guests and members who are NOT editors{/ojaccess}
{ojaccess editor,special}shows to editors, administrators, and superadministrators{/ojaccess}

If you are Rok member, you can see it works same as rokaccess, but this plugin is joomla 1.5 native version