Grayceon - Progressive metal where the lead vocalist also doubles as the 'lead' cellist in the group.
Songs To Check Out: Pearl, We Can, Shellmounds
Diablo Swing Orchestra - Avant-garde swing metal with a whole host of other sounds present. Lead singer has Nightwish-esque operatic vocals or a more 'normal' singing voice. Music is just a helluva lot of fun to listen to.
Songs To Check Out: Balrog Boogie, Ragdoll Physics, Tap Dancer's Dilemma, Honey Trap Aftermath, Justice For Saint Mary
Kylesa - Sludge metal with a heavy dose of psychedelics. Laura Pleasants is one of the bands' guitarists and singers, but she's become more and more prominent with each release. The vocals aren't very harsh, but they are not exactly clean either.
Songs To Check Out: Tired Climb, Steady Breakdown, Crowded Road, Exhale, Drop Out
Stolen Babies - Sorta metalcore-ish avant-garde metal. Dominique Persi is the lead singer and lead... accordion-ist for the band. She uses a combination of clean vocals and screams.
Songs To Check Out: Splatter, Dried Moat, Year Of Judges, Lifeless, Spill!
Florence + The Machine - I'm not as familiar with them as I am with the above, but I like what I've heard. Kinda indie rock, pop-ish I guess. Lead singer Florence Welch has a tremendous voice. Definitely worth checking out if you're in the mood for something a bit different.
Songs To Check Out: Dog Days Are Over, Girl With One Eye
Arcade Fire - More of an ensemble really, but the band does feature several women who play various instruments and sing. Just pretty cool indie rock.
Songs To Check Out: Neighborhood 1 (Tunnels), Wake Up, No Cars Go, Black Mirror, City With No Children, Sprawl II (Mountains Beyond Mountains)