I know! It would be horrible to have the service be free, and integrated with Google's other search and social features and therefore more visible to the world!
THE HORROR!!1
[edit: not to mention company lawyers looking to sue some NDA violating employees]
Perhaps you could grep for common libraries like "ffmpeg" and make a guess as to what sort of software it is. Maybe a video editor/player in the case of ffmpeg. Once you figure that out, you could show advertisements for the same sort of software.
So it's already free, it's already integrated into Google's search, if I want to be social about what I'm coding I can easily share it on G+...
What problems would be solved by doing anything differently?
If Google bought it and nothing changed I'd be happy!!! However, I don't think that'd be the case. Things would change and I suspect for the worse, since it's not a big cash cow like search is.