youtube-dl is a command-line program to download videos from YouTube.com and a few more sites
The qBittorrent project aims to provide an open-source software alternative to µTorrent.
Your Spotify is a self-hosted application that tracks what you listen and offers you a dashboard to explore statistics about it! It's composed of a web server which polls the Spotify API every now and then and a web application on which you can explore your statistics.
MeTube is a self-hosted web GUI for youtube-dl (using the yt-dlp fork) with playlist support. It allows you to download videos from YouTube and dozens of other sites.