Continuous Integration. Don't understand how anyone wants to run a software project without an independent and automatic test-runner.
For Github this means using Travis CI, CircleCI, Appveyor etc
These projects too will benefit from a independent CI-service validating their commits.
Generally speaking you'd set up your own "synchronisation channel(s)" for such tools e.g. mailing lists.
The point of github / gitlab / etc is to have all the tools in one place, nicely integrated
I personally feel gitlab/github are useful from community and collaboration aspects - there is nothing I couldn't do without github on my solo projects from purely technical point of view, it's strengths are issue tracking, pull requests, wikis, distribution of code.