Male: Greg Graffin, Britt Daniel, Jeff Buckley, the guy from Stereophonics (I'm blanking on his name), Zach Condon, Peter Murphy, Bill Janovitz, Neil Hannon (The Divine Comedy), Elliott Smith
Female: Carol van Dyk (Bettie Serveert), Neko Case (second by, like, a hair), either Kim or Kelly Deal (whichever one sings "Drivin' on 9" on Last Splash), the lead girl from Wir Sind Helden, PJ Harvey, Dani Linnetz (The Inklings), St Vincent