Doing the $LORD's work. I haven't contributed much to RethinkDB but it's such a great piece of software. It was doing things right basically from the beginning -- also has great Jepsen reviews[0][1] (if you ever need to defend it -- it's one of the better ones).
The Admin GUI was one of the things that made it an instant click for me -- it's a fantastic tool and I want to run it as a service someday, feels like the only way it can gain marketshare again is if some company pushes it sustainably.
Having a built-in Data Explorer is clutch. You can get visibility into your database without having a Ph.D in computer science. It's beautiful.
After I finish up a couple projects I want to help modernize the Data Explorer. It ain't broke but it needs some love.