Previewing Content for Registered Users
One of the options that Joomla offers is whether or not to display content to site visitors who do not have the appropriate access level to see it.
The Problem:
Normally, I think this is an easy decision: most of the time it's less of a hassle to just hide content from those who don't have permission to access it. If I'm managing a site that includes documentation for a small set of users, like an organization's officers or shareholders, I avoid any questions raised by those who think they should have permission to see that particular content.
However, I'm working with an organization whose value is a) its membership network and b) the content provided by members to each other. It's tough to sell the notion of premium content without providing some clue as to how much of it there is, and what kind of content it might be.
The Solution:
At first glance, this looks like an easy one. On the main page of the article manager, the configuration control panel includes an option called "Display Unauthorized Links." Enabling it is the first step to solving this problem, but it's not the only step. Remember that Joomla is very specific: in this case, link refers to links to articles and functionality, but it does not refer to the display of menu items.
In my case, I had created: a menu item, a category, and a section for storing my premium content. In order for this to work all three of those items need to have their access levels set to Public. The only item that I restrict to registered members is the article itself.
Be sure to test your solution: for some reason my site reverted to a very generic, ugly Error 403 page (not authorized). I wanted something a little more user friendly, and found this tutorial quite helpful in creating a new custom 403 page that encourages users to register, and keeps the look-and-feel of the site.