Open source software is inextricably tied to the idea of giving it away. Projects open their code for a number of reasons -- to better the codebase, or to allow others to bend an application to their own needs. Maybe the reasons are entirely altruistic, or maybe the altruism is the happy side effect of more project-centric decisions.
Of course, the open source approach doesn't just help code, or simply act as the framework for strong applications. The desired end result of any application is to improve the life of the user in some way. It sounds like hyperbole, perhaps, but if an application isn't making work in some way easier (or play more fun), it's not an application you'd want to use again.
