The list below is not exhaustive. There are thousands of ports available and multiple end-user apps. Here we list what is well-tested and can be advised to install.
There are a few options for modern multimedia players, but the first best is QMPlay2.
You may also try mpv and mplayer (the latter may be preferred on resource-constrained systems).
YouTube: unless you need a command-line app for some reason, just use QMPlay2.
Here choices are numerous. Try and see what you prefer: qmmp, DeaDBeeF, lollypop, guayadeque, audacious, rhythmbox.
For hi-fi audio blackomega can be considered.
There are a number of TUI players: musikcube, cmus etc.
Rawtherapee is the way.
Claws-mail for GUI and nmail for TUI.
transmission-x11 and deluge for torrents.
Then, amule, nicotine-plus, eiskaltdcpp and gtk-gnutella.
There are clients for XMPP/Jabber: dino, profanity, Discord client – abaddon, apps for Tox and IRC.
The best sFTP client is FileZilla. To download videos use Parabolic or tartube.
There is also a catgirl-downloader.
fastfetch.