Over time, I've slowly found more and more interesting self-hosted tools that either replace other paid services or add something completely new to the mix. Most of these tools are free, have great Docker support, and make sysadmin that much more enjoyable.
Plex is, if you haven't already heard of it, is an amazing 'roll your own' media website. For me, it replaces Netflix, Spotify, and pretty much any other tv/music hosting service. There's a great docker container for both x86 systems and one for arm, and a wonderfully supportive subreddit dedicated to the service.
docker - subreddit
This is a service for downloading music from Deezer. The main advantage with this platform is the amazing tagging capability and consistency it provides. This meshes with Plex especially well. Most music can be downloaded perfectly tagged in FLAC and it can also download Spotify playlists as well! Legally, you must have a premium Deezer account, however the service still works without a premium account. Note that the docker container linked is not official.
This is a very clever container which bundles OpenVPN and a Transmission Web Client in a single container. This way, you can run a Transmission instance which will download through a VPN Service (I recommend PIA as they have port forwarding) while leaving the rest of your net alone.
Headphones is a utility to download music using a torrent client (such as transmission). It's fairly well supported and, although I prefer Deezloader Remix for it's perfect tags, Headphones is pretty great when Deezer is missing music.
A brilliant tool that allows for automatic downloading of TV Shows with good media format filtering and tagging. It correctly names files, so it works well with Plex as well.
Sonarr but for movies. Enough said, get it.
Jackett allows for Radarr, Sonarr, and Headphones to use common public trackers rather than NBZ providers. Highly recommended.
Nextcloud is basically self-hosted Google Drive. It features automatic photo uploading, 2FA, collaborative editing, and it's comforting to know that all your data is as secure as your home server.
This is a rust rewrite of a great password manager, designed to be lighter than the full version (which makes sense for personal cloud deployments). It supports the well-made Bitwarden Android app and browser extensions.
This is an excellent tool that can be used to manage, edit, update, and monitor docker containers. This also makes deploying this many docker containers very manageable.