Shmoop has now introduced a new subject - Music! Shmoop has already been a great resource for Literature and History. Written by university professors and by teachers, Shmoop aims to make "writing and learning more fun and relevant for students in this digital age".
Though the music database is just beginning to evolve and therefore has limited songs, the information is extensive, entertaining and enlightening. For each lyrical line, the Shmoop editors give a "quick thought" and "deep thought". In fact, you can listen to the song as the editorial notes pop-up at the appropriate place in the song.
Incidentally, I knew that Paper Planes by MIA was a violent song, but Shmoop provided some real eye-opening information about the meaning and the artist's biography.