Robyn's stuff is a paradigm of electropop. It's an unofficial genre as it is, but whatever it is that electropop sounds like, it sounds like Robyn. I saw her at Bonnaroo and it was a great show. She's a tiny girl. I'm thinking like 4-10, 90lbs. But she rocks out when she's on stage.
I have only listened to Metric's most recent album, and I loved it. They're on my list of groups to back-listen.
Little Dragon chick has a mindblowingly good voice (here is another track I like: shuffle a dream
). Big Boi is apparently a big fan of hers as well, as she co-wrote three tracks off his most recent album, and was featured on all three until a business/legal issue between their respective labels caused her to be pulled off Mama Told me and replaced with Kelly Rowland. But she did several live performances before it got ixnayed and she did it better than kelly (though I'd rather have sex with kelly). Big Boi ft. Little Dragon -- Mama Told me (Live)
Of every artist/group in the list, Ellie is the one I've heard the least of. I've never actually heard one of her albums in its entirety. I guess I should get on that.