Many people use lyrics to teach English as a Second Language. That method works well. Students learn new vocabulary and it is a more interesting way to illustrate grammar points. You can also use lyrics for writing practice. Have your students write a new verse; have them continue telling the song’s story.
I’m intrigued with using the sonic aspects of music to stretch students minds as a way to help them improve their writing. For example, play two versions of the same song and have the students write about how they are the same and how they are different. Another method is to play an instrumental and have the students write about how the song makes them feel. Play some World music and have the students write about what country they believe the song is from and why.
This approach does not work with all students. TOEFL and other university-bound students may find this approach to be foolish. However, it is a useful method when used appropriately. Sometimes the best way to explore a language is to put the academic interests aside and just be creative and have some fun.