I've got a student who's working on starting a company around a configuration management system he wrote while he was working for BYU and has licensed. I've seen the system in action and it's pretty good. Shops with over a dozen machines could use something besides a spreadsheet to keep track of all this.
He's been working on various parts of the business and decided he wanted to open source the software and build a business around the open source code base. I don't know much about that business model, so I hooked him up with Matt Asay. I'm sure Matt will be able to give him some pointers.
Just this week, I published Scott Mace's interview with John Roberts, the CEO and co-founder of SugarCRM, an open source CRM system. John and Scott spend a lot of time talking about open source business models and how they work. There's the traditional pay-for-support option that Redhat and jBoss have made famous and the hosted-services option that's becoming more popular with the growth of SaaS.