Integrated domain registration solution for multisite

In WordPress.com there's an option for domain mapping but also to register/renew a domain name.

Is there a solution/plugin/best practice on how to offer something similar on a multisite server for our clients?

It would be nice to have the domain auto configure the WWW record to the proper IP address and setup email services.

I have a couple "convoluted ideas" on how to make this work but wondered what others have done?