My own experience working at CoreOS is that many of our projects exploit self-referentiality as it's a particularly useful property.
Off the top of my head:
- Quay.io, our registry service, is built and deployed by itself
- Clair, our static analysis tool for detecting security vulnerabilities, analyzes itself
- Tectonic, our enterprise Kubernetes distro, is "self-driving" and manages itself
- discovery.etcd.io, a service we run to make it easier to bootstrap new etcd quorums, is just a quorum of etcd nodes
