My favorite use of this is peer-to-peer transfer of Docker images. The Docker CLI only allows you to use registries authenticated with HTTPS but there's an exception where it allows HTTP transfers over localhost.

So, if you use SSH tunneling to forward a port from localhost to a remote, then Docker unwittingly pushes to a remote. This is super useful "off the grid" with robotics/embedded applications where you don't want to bother with a registry and a good Internet connection.

Example, docker pussh: https://github.com/psviderski/unregistry