To conclude this week's tour of free goods and how they can be good even though they are free, let us look at our own profession. RePEc is a free bibliographic database that is free for all participants: authors, publishers, readers. Interestingly, it does not even rely on a grant, as its budget indicates.
Somehow, RePEc manages to find the resources from various sponsors providing hardware, hosting and bandwidth, as well as numerous volunteers. Incentives seem to be aligned for everyone to want to provide help for RePEc. Obviously, publishers want to make sure their material is listed, thus they provide records for free. Various volunteers seem to participate either out of pride of doing something good for the community, or to satisfy some (public) service requirement their job may have. And end-users are just happy to find a free service that is better than the pay services out there (Econlit and SSRN come to mind).
For non-economists, there is always Google Scholar, but for Economists, RePEc is unrivaled.