I've started on my sequel to Crow's Rest (its working title is No Man's Land) and a couple chapters in I realized I was having trouble finding the tone of the book. In the past, I haven't worried about that too much in the drafting stage, but with this book the tone is going to direct several plot-forks in my outline. (Plot-forks are too real things! Don't make me show you my literary license)
I was thinking about how when I would come back to the Crow's Rest draft after an absence, two songs helped get my brain in gear for writing (Firethief by Karine Polwart, and the song I wrote for the book which will appear in the book trailer). But No Man's Land didn't have a song just yet, so there wasn't a tool I could use to drop me into the story.
To fix that, I spent some time rewriting lyrics to an old English folk song, variously called A Blacksmith or Blacksmith Courted Me. Now I have song lyrics that are particularly relevant to the story and plot, plus singing it puts me in the frame of mind to continue in the Crow's Rest world.
Do you ever use music in this way? It's a little more specific than a playlist, but I'm sure they'd be considered close relatives!