Hello, Tom!
As of the time of writing, none of the other FOSSBilling members have responded with any potential uses we may for the server.
Regarding your idea, VM functionality within FOSSBilling would be really great, but truthfully there just isn't the contributor power to do so.
I'm still really only the active fully contributor to the project and I myself and swamped with normal work and my own life. Yesterday I worked a 15 hour shift and I just don't have the time nor energy to expand FOSSBilling's scope / take on a new project.
It is a great offer though and I am sure you'll find someone who can make great use of it.