I'm currently experimenting with the UI for my upcoming Gear VR star gazing application. Virtual reality user interfaces are really interesting, since they have to work so differently from a standard 2D UI. One possible realization is to have interactive elements as actual 3D objects in the scene. This can be fun! For my app, I am thinking about putting a "time machine" into the scene, which will allow you to move forward and backwards in time for different views of the sky. Much cooler than having a 2D number selection thingy. Nothing to show yet, but stay tuned!

How to select and activate anything in a VR scene can be a science. For starters, I recommend having a look at Unity's VR Sample Scenes project. It includes a bunch of useful scripts for reticles, selection radials, VR input handling, etc. This looks pretty convoluted at first, but once you get your head around it, it offers some nice ideas on how to architect an application UI.