Fully hosted

Here is an interesting thing you can do with the Fully Hosted setting.

Mirror a directory using a sub-domain
Say you have a subdirectory on your site called "dreamhost.com/example" and you would also like to have a subdomain "example.dreamhost.com" that hosts the same files. To set this up you will need to use the power of the Dreamhost customizable hosted directory settings.

The first step is to add the sub-domain. Log into the Dreamhost panel. (https://panel.dreamhost.com) and go to the [Domains \ Manage Domains] section. There you can click the [Add New Domain / Sub-Domain] button. In the settings you would enter this: Then press the [Fully host this domain now!] button.
 * Domain to host: "example.dreamhosters.com"
 * Run this domain under the user: the same user as the primary domain "dreamhost.com"
 * Web directory: here you set the sub-domain to host from that subdirectory; so enter "dreamhost.com/example"

Now your new sub-domain example.dreamhost.com should host the dreamhost.com/example/ directory.