HoloLens is not going to ship to consumers just yet, but developers will have a chance to develop exciting solutions for it. Galaxy Explorer for HoloLens has been in the works for quite some time, but it is now ready to go. It is an open-source app that was developed in 6 weeks as part of the Share Your Idea program.
As the name suggests, this app lets you explore the stars and planets on your HoloLens. It can serve as a starting point for your own projects. Microsoft has shared more on this project on GitHub.