I am actively participating in a few graduated sites and a private beta. What I normally do when I become active somewhere is to add the site into my "your communities" list dropdown.
However, I noticed that it is not possible to add sites in your own "Your communities" if they are -still- in private beta.
Could we have this option?
Note this is pretty related to Have private betas in "Your Communities" list in the Stack Exchange dropdown and what was then mentioned in comments there, but wanted to make sure it is requested in a stand alone post, since in that post they are asking for something more generic.
Hardware Recommendations
site in the drop-down list from like it's second day of graduation (into private beta). So, I think you can manually add them.