For a while now I’ve been toying with the idea to test out Drupal’s subdomain module. This allow you to create unlimited subdomains for your domain and link them to content. As an example you can have various content categories, and for each of those categories have a subdomain.
We launched it at http://www.greatblogsite.com/. One of the categories we have is Dog Training Tricks which then links to http://dog-training-tricks.greatblogsite.com/. This is great if you have a community site and you want to have each user have his or her own subdomain name.