When I played in person, I used quite a bit of music, mainly Dead Can Dance, historical folk, and classical. I didn't change it up to match the current actions in-game, because (a) combat takes longer than a concerto, and (b) changing physical media breaks the mood more than having only-quasi-appropriate music playing.
I play remotely now, so it's more difficult than having a stereo in the same room with the group.
Roll20.com previously had a contract with SoundCloud to stream the GM's choice of music, but that functionality disappeared a year or so ago. Hilariously, SoundCloud had plenty of bad remixes of mainstream music, barely evading copyright problems.