I run a web hosting company in Wisconsin that is using Virtualmin Pro, Virtualmin GPL, and Cloudmin to manage our servers and to provide user panels. My company particularly specializes in customized Drupal hosting, but we also have plain ol' ordinary hosting packages available.
Our system is integrated using Virtualmin for user panels, Cloudmin to manage VPS systems (our shared hosting is running out of VPS Xen systems) and our physical servers. We sell shared, VPS, and dedicated hosting. We use WHMCS to sell domains, SSL Certificates, and our hosting packages. But we also do customized configurations if you need them.
Feel free to talk to us, particularly about any specialized Drupal needs you may have.