In some situations, there is a requirement to be able to preview unpublished content without logging into Sitecore.  Perhaps a marketing director needs to review the page before it launches, or maybe a partner needs to review a press release prior to the official publish.  The traditional Sitecore preview capability forces you to log into Sitecore in order to be authorized to view the content in the Master database.  So how do you get around this?

Mark Ursino, a Sitecore MVP and the author behind the Fire Breaks Ice blog, wrote a great post on the subject: How to Setup a Sitecore Site to Review Content Before Publishing.  The essential setup is that you need a new ‘site’ in your Sitecore configurations that points to the Master database instead of the Web database.

Mark outlines some caveats with the approach:

• The HTML output caches need to be manually cleared if you’re modifying cached content and need to preview it. This is because these caches are normally cleared on publish. One possible way to get around this issue is to set the size of the HTML cache for the preview site to 0MB, but I have not tried it.
• If you use Lucene indexes, they will not be updated. This is because your indexes are probably indexing web content and get added during publish operations.

In addition to these caveats, another situation to bear in mind is the use of SSL certificates.  If you have bound your entire site to a particular domain/certificate, you will get SSL errors if you access the site with a different URL.  Remember to setup your site with multiple ports or IP addresses to allow for multiple certificates.  Read more on SSL configuration for IIS here: http://technet.microsoft.com/en-us/library/dd163531.aspx.