On a live episode of This American Life, Joss Whedon played the piano and sang a song from Commentary! The Musical.
(Dr. Horrible's Sing-Along Blog)
(Legend of Zelda)
(Doctor Who, Sherlock (BBC))
Little known fact, The Thing enjoyed a successful career as a lounge musician after the events in Antarctica.
(Warning: contains disturbing images from the 1982 film "The Thing," and some salty language.)