I am referring to the playground list of libraries. I do realize that they are all over the place but I think with encouragement of the Arduino team one could get the contributors to deposit their libraries on your site as well for download.
Having said that I also realize that some contributions are made in order to draw people to a specific site and maybe to sell something to them. I think it is worth the effort to try and convince contributors to support your repository for the sake of the tool and the many coders out there that can benefit from it.