Movie: Phantom of the Opera (2004)
Minnie's an experienced singer, but she didn't actually sing in her performance in Phantom of the Opera; since she had no training in opera, her vocals were dubbed. But one song sung by Minnie (and written by Andrew Lloyd Webber) did make the film: "Learn to Be Lonely," which played over the closing credits.
Driver's secondary career as a singer/songwriter has unfolded quietly. She's released two albums, Everything I've Got in my Pocket (2004) and Seastories (2007), with help from folks like The Wallflowers, Ryan Adams, and Liz Phair.