I made https://stevenwaterman.uk/musetree which is a custom frontend for OpenAI's MuseNet. I've used that to generate music that I use on my Twitch streams, games, and other things. I'm not kidding myself that it's as good as human-written music, nor is it truly ai-written music (as there's a lot of human selection in the process), but people frequently comment on the music and enjoy it, without realising it's AI-written

Some examples:

https://github.com/stevenwaterman/Twitch-Overlay/raw/master/...

https://github.com/stevenwaterman/NoTimeToStalk/raw/master/c...

* Edited to fix the link, my bad