This is a bit out of left-field, but getting back into intensive usage of Virtulmin/Webmin after a number of years an idea occur keeps bugging me so I’m going to just spill the beans:
While it is a joy to use compared to cpanel etc. I find the main thing about it I like is the support provided by google results returning relevant posts in the various fora on the virtualmin.com site. The main thing that might help further this strength would be to use something like the Ergo Reasoner to consolidate the incrementally-acquired knowledge while supporting customers in these fora, in a more useful form. If hosted at virtualmin.com this knowledge base could prove invaluable and may even provide a superior business model.