Scenario... We want to use the name field of our Market object for URLs like... foo.example.com/groups/view/groupname bar.example.com/groups/view/groupname ...and other similar URLs, basically using the subdomain as a key for the app to know which Market (there is a markets table where the subdomain field corresponds to Market.name) to use. In this example, both pages are viewing the group homepage for ''groupname'' group. There could conceivably be a group called ''groupname'' in both the ''foo'' and ''bar'' market. We COULD use /group/view/id, but using the name makes me happier. I''m aware of using filters in application.rb to use the subdomain as a key, and I could then access @market throughout the app to figure out where I am, but it would also be nice to have some rule that sends all URLs that have a subdomain to a ''markets'' controller, for example. Does this make sense? I think the basic question is can you do things with subdomains in routing, instead of just using the filter in application.rb to set variables that your controllers handle?... -Matt