In-game music?
The GM and a few of the players in a game I'm in routinely post links to YouTube videos...either characters singing during their off-hours, or listening to music to hype themselves up going into combat, stuff like that. It doesn't autoplay...if you don't click the link, you don't hear the song (and about half the time, I don't bother...and probably 2/3 of the times I do click the link, I listen to about 30 seconds to get an idea of the tone of the song and then go back to the game, minus the music. I admit it, I'm very picky about music, and while a lot of the songs they pick are appropriate to the situation, I just don't enjoy them all that much.
That said, I have put together 'soundtrack playlists' (back when they were still called 'mix-tapes') for entire gaming sessions or even campaigns that I played in.