[indigochill]

> I think GitHub should really have a way for users of your repository to somehow illustrate that they're using your project

I kind of use forking that way (although more when I like a project, it's not necessarily a promise that I'm using it anywhere). This ensures that I have a copy of the project in the state that I originally liked. Then if the project is either (a) taken in a disagreeable direction or (b) deleted, I still have my local copy. I can also always update from upstream if future development occurs that I want to benefit from.

That said, I don't fork all the open source packages I use, although maybe I should.