I'd like to make a three-part argument regarding Leslie Feist's awesomeness:
1 2 3 4, on Letterman
Sealion, on some TV show I can't identify
Mushaboom, on Jimmy Kimmel
I saw Broken Social Scene in the tiny 400 Bar in Minneapolis (they barely fit on stage!) a long while back, when Feist was still performing with them. She wasn't even onstage for all the songs, but she turned a really good show into one of the best I've ever been to.