If for no other reason, "Nothing Really Matters" is significant as it's the final studio recording by Madonna to feature Niki and Donna, and their only appearance on 'Ray Of Light'. Actually, I believe they appear on just five post-'Erotica' studio recordings with Madonna. Prior to "Nothing Really Matters" they heavily featured on dance remixes of two 'Evita' songs: "Don't Cry For Me Argentina" (for which Madonna re-recorded her lead vocals) and "Buenos Aires" (for which she did not). They also made a single appearance on 'Bedtime Stories' for album opener "Survival", and I believe they contributed uncredited vocals to the soundtrack single "I'll Remember" earlier that same year (backing vox sound identical to those on "Survival"). I want a reunion!