Conjure One has music written by a guy, but all the vocals are guest female vocalists. At least, it was so for the first album. I haven't listened to anything but the self-titled 'Conjure One' album. Definitely can recommend that album.
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Controller.Controller was a groovy band. Put out two albums then broke up when the singer decided to pursue her career outside of music. They put together some good music while it lasted.
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Dragonette. Love their first album. They have a second one out now that I haven't had a chance to pick up yet.
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Metric, Broken Social Scene, and Feist have been mentioned already, but I don't think anyone has pointed out Emily Haines's solo material.
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Oooh, boy! Time for LIGHTS! Probably my favourite artist on this list.
LIGHTS - Saviour
LIGHTS - February Air
Also, check her YouTube channel for the ongoing Audio Quest animated comic book thingy.
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Chances are, if you like piano in your music, you'll like Sarah Slean.
Sarah Slean - Sweet Ones
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Whew, yeah, that's my list of favourite female singers/songwriters, excluding jpop/jrock. And interestingly enough, all of the above are Canadian.