That's really cool! A very good overview of the standard library and how to build network services with it. Also interesting in the standard lib is textproto, it's a super simple text based protocol you can use for building client/servers:
The best tip imho is to use `vimtutor`. It's installed on every machine that has vim (to the best of my knowledge) and provides an interactive tutorial that builds on itself to teach vim knowledge. It's really cool, if you haven't checked it out just fire up a terminal and give it a play.