How up-to-date is your company's software development business plan? Dennis Stevenson had an interesting article in his ITtoolbox blog on "Software Development as a Service." This would refer to IT departments that choose to outsource software development when it is not a core competency or competitive advantage for their business (the same arguments that are used for outsourcing applications and application management in the Software-as-a-Service model). Of course, this is no different from outsourcing as we already know it, but that's his point... It follows the same "as a Service" model and he urges IT customers to consider it in the same way (in terms of pros versus cons, what to look for in a provider, and what types of projects to do "as a Service" and which to keep in-house).
Of course, the same considerations could apply to an ISV as part of their software development business plan...
Perhaps there is some software development that it makes business sense to outsource? Should you do Software Development as a Service? Could be as an open source model, or certain components of your portfolio of offerings, or other ways that optimize your business model. The key consideration is to keep in-house that software development that provides your business advantage: do not outsource the "secret sauce."
Perhaps you could provide additional software development services for your customers as a software consulting business component of your plan? That spins it the other way. If you sell your software product to large business, there may be related software development or integration services that your customers need. Do they need to integrate your application with others in the enterprise? Do they need customized modules?
If you're not considering this as a component of your software development business plan, perhaps you are leaving revenue on the table.