Tangent - is there a Docker Wherehouse where I can find dockers to DL an run, that HN would suggest and some use cases of "pull a docker from here to do X - super cool"
The awesome selfhosted* list is a pretty good resource. While it does mention if there's a Docker container, I've found a few of the services without one listed do actually offer one, just have to search for it.
Docker hub has been one of the primary registries. Each of the cloud providers typically have their own concept for docker or image repositories, and you can build docker files locally of you have a docker file in source code.
* https://github.com/awesome-selfhosted/awesome-selfhosted