1) Nuclear - Desktop music player focused on streaming from free sources (in beta phase):
https://github.com/nukeop/nuclear
Nuclear Mastodon account: @nuclear
2) Pidgin - IM with options to add various third party plugins which enables you to use facebook chat, steam chat, etc, XMPP included.
https://bitbucket.org/pidgin/main/src
3) Synchting - cross platform peer to peer file synchronization, also available on f-droid:
https://github.com/syncthing/syncthing
@ccppurcell
Yes, it works but it doesnt use xmpp. You can check out how to set it up on pidgin site.