Episode 4.01 - "My Old Friend's New Friend"

Scene: J.D. imagines his clock singing (the actual song later repeated as Turk dances around the car).
"Rapper's Delight" by Sugar Hill Gang. Album: various

Scene: The patient sings at J.D.
"Anything For Love" originally by Meatloaf. Album: various

Scene: J.D. sings the lesson-learning piano music.
Music cue from original Scrubs score by Jan Stevens.
Sung by Zach Braff.

Scene: The patient sings at Elliot, and Carla feels like a third wheel when Turk and J.D. are together.
"All By Myself" by Eric Carmen. Album: 'Eric Carmen'