Here are some my favorites:
There's not much specific to Node.js, but it will be helpful to learn how to create custom Observables so you can wrap more imperative APIs or make utilities. Ben's article above will definitely be the best resource for that.
While you're learning, keep an eye out for v4 vs v5 documentation and libraries as some things changed between those versions and people often get tripped up trying to use v4 code or APIs with rxjs v5. Hopefully this shakes out as time goes on. There are still some active efforts to mitigate this.