LinuxMusicians

mmm torrent.linuxaudio.org would be a good idea I guess.

Anyway, transmission the bt client can create *.torrent files.
You uploaded that file to the tracker, download the torrent and start seeding.

Oh, forgot. You could also use SoundCloud and enable downloads.
Or clyp.it
Or https://mixtape.moe

I think most torrent clients allow you to create torrents. Then upload the torrent somewhere.
Archive.org allows you to upload music as well as torrent files, for example https://archive.org/details/revolutionsolution/