I've always been one of those "the whole world has a soundtrack" sorts, so music is a pretty important component. I do tend to have songs or playlists for stories, as well as for regular characters; usually, however, it's stuff I've run across and been struck by, rather than actively hunted down for the purpose. It interests me how often The Perfect Thing is what would seem at first glance to be the most incongruous, and/or done by an artist one would never think of if one were deliberately looking.

Not counting things like Lyric Wheels, I can think of only two pieces I've ever done in my life that could possibly be called songfics. And even then, it was more that the music was a framework or an inspiration -- not something that actually appeared in (or could be inferred from) the story in any way.