The famous Eminem and Dr. Dre collaboration "Guilty Conscience" has Dre and Eminem portraying Good and Bad Angels, respectively, for various people caught in moral dilemmas. Dre wins the first argument, it's unclear who wins the second, and in the third (whether or not a man should murder his cheating wife and her lover when he catches them in the act), Eminem successfully points out that Dr. Dre has his own history of violence (referring to the Dee Barnes incident) and has no business telling people not to be violent. Dre agrees and they end the song by urging the man together to commit the murders.
In short, Dr. Dre... is not the world's best Good Angel.
P!nk's song "Stupid Girls" has a little girl debating between following her expected gender role, and going outside to play football. P!nk plays both a devil and an angel on the girl's shoulders to represent each of these.
Santana's song "Put Your Lights On" (sung, and actually written, by Everlast on Santana's Supernatural album) has the lyrics:
There's a monster living under my bed, whispering in my ear
There's an angel, with her hand on my head, she say I got nothing to fear
OneRepublic's song "Love runs out", the singer mentions having "an angel on my shoulder and Mephistopheles".
Schaffer The Darklord has a track on Manslaughterer titled "The Other Devil", a twisted version of this trope which mixes with Crosses the Line Twice by having STD and a squeaky-voiced puppet version of himself play the role of two devils, on either side of Popeye, with one attempting to coax him into amoral actions, and the other pushing him to do something even worse.
Nickelback's song "Animals", makes reference to this.