If you are referring to anonymously accesible Confluence (wiki) space, you can achieve this.
Grant anonymous user the 'can use' permission in the global permission setting at https://domain.atlassian.net/wiki/admin/permissions/globalpermissions.action. Then, in your space, grant 'view' permission for anonymous user, for example at https://domain.atlassian.net/wiki/spaces/spacepermissions.action?key=SPACEKEYHERE
It is similar to http://confluence.atlassian.com/display/DOC/Setting+up+Anonymous+Access. Is this what you are looking for?
In the URL https://domain.atlassian.net/wiki/admin/permissions/globalpermissions.action, change the domain.atlassian.net to your own OnDemand domain.
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
We're bringing product updates and pro tips on teamwork to ten cities around the world.Save your spot