One of my goals for the #homelab is to self-host my code with a CI/CD stack, setup a pull through cache for Docker images, NPM packages, and Composer packages for my day to day development work.
I'm also planning on setting up an APT cache of Debian since all my servers, virtual machines, and my desktop run Debian.
Maybe someday I'll setup a Steam cache but I'll need to expand my storage significantly for that.