How to deploy multiple rails app on a single IP (Apache + Passenger)?
Yes. The Passenger guide calls this "Deploying to a Sub URI"
http://www.modrails.com/documentation/Users%20guide%20Apache.html#deploying_rack_to_sub_uri
Additionally, you could set up a standard virtual host setup and use your hosts file to make up a domain you like. This would only work for testing of course, as anyone who wanted to see the apps would need to have the same entries in their hosts file, but would be fine for development.
Domains don't need to be hosted in the domain name system to be useable for virtual hosting.