Is there a Plugin to autmatically create 3rd level domain?

I am setting up an appointment scheduling site using the appointment plugin.
What I want to do is automatically setup a 3rd level domain area when a visitor registers on my site, creating their own space and with appointment plugin functionality.

I ned the appointment plugin to be immediately available to a newly registered member, in their 3rd level domain area.

Example: say my site is http://www.schedule.com, and a company registered and selected "mystore" as their domain id, so their 3rd level domain would be mystore.schedule.com.
If this capability is not available, then the next best option would be http://www.schedule.com/mystore

By setting it up this way, a company could register, a 3rd level domain is established automatically, then they can setup appointment profiles for all of their agents / employees (within their 3rd level domain)