I've used music to focus and define emotional energies for magical purposes, as well as a "theme song" for certain types of work. Metal I have found very useful for aggressive forms of operation. Softer music for conciliatory and harmony promoting works.
I've found the energy in certain types of music is also good for promoting perception in study - for example, sigil study to Meshuggah makes me sense those fissures between worlds embedded in symbols.
I had read of using music in working from a couple authors, but the idea was activated in me by example when I was in the service. I went to a female friend's barracks room to pick her up for chow time and the door was open, as usual. But when I walked in I saw her dancing in her underwear to Madonna while burning incense. She told me she was casting a love spell on a newly arrived male Marine who was some corn fed Midwest Christian type. She got her wish, but I felt bad for the guy partly because he was being made a fool of - he became dazed, obsessed, undisciplined and fretting over her. Plus I knew things about this woman that well... let's just say she had a reputation. But whatever the example may be, what works, works.
I do not listen to Madonna. I refuse to. I believe that when she kissed Brittany Spears onstage she was actually cursing her.