Christian ska band Five Iron Frenzy wrote a song called "A New Hope" about what happened at Columbine. The band is from Denver CO, and band member Micah Ortega's sister was one of the students trapped in the choir room during the massacre.
Members of KMFDM, one of the bands to which Harris and Klebold were avid fans, had formed a group called MDFMK and wrote a song called "Witch Hunt".
The massacre inspired Finnish symphonic metal group Nightwish to write "The Kinslayer" for their Wishmaster album (1999). The song references the victims (9 men, 4 women) and shooters and contains a conversation between Nightwish singer Tarja Turunen and guest singer Ike Vil that are supposed to be a conversation between one of the killers and one of his victims.
Napoleon referenced it at the end of a Outlawz song "The Good Die Young" on Still I Rise, not to be confused with the D12 song released on D12 World approximately 5 years later.