Sometimes you need to publish a site anyone should be able to see or maybe even add information to. In order to do this you need to have Anonymous access enabled on the site. One step many people miss is that anonymous access has to be enabled at the web application level otherwise it is not going to be available on your site. Keep in mind that there are different levels of access you can give anonymous access so be sure to be as restrictive as possible to protect your site but still functional.
The following site offers a very detailed tutorial on how to activate anonymous access at the farm and site level: http://www.topsharepoint.com/enable-anonymous-access-in-sharepoint-2010