Broken Social Scene has 4 female singers, but that's only because the lineup rotates every year.
Metric's Emily Haines - she does her own solo stuff which is incredible as well.
Stars' Amy Millan.
VersaEmerge's Sierra Kusterbeck.
Plumtree is an all-girl band, disbanded now though.
Hannah Georgas, who is more a solo artist but has a backing band.
Yeah Yeah Yeahs' Karen O.
Tegan and Sara.
A Fine Frenzy (It's more like a NeverShoutNever deal - she's a solo artist under a title. Really really good though.)
And The Academy Is...'s William Beckett.