We'll add an option for project leaders who want their projects explicitly promoted outside of DoerHub to be able to chose to be featured. We keep the quality of the network really high, so some want to stay inside. There are actually entire universities using DoerHub for cross-discipline projects, and some of them want to stay in a closed environment.
It would be really nice to have a "Explore" feature similar to github, where you can see projects, and maybe be able to search for tags. A big call to action button on the main page linking to the explore area would really allow people to look at projects and see how the site is getting used.