Viva la vida by Coldplay, sang by Princess Luna.
My immortal by EVANESCENCE, sang by Princess Celestia.
Good time by owl city, sang by pinkie pie and Discord
I'm excepting songs and suggestions.

Amazing Picture of Karaoke Sparkle by vegemiteguzzler
Link to picture: http://browse.deviantart.com/art/Karaoke-Sparkle-322290535
Link to the artist: http://vegemiteguzzler.deviantart.com/
You'll have to copy and paste the links to get there.
Be sure to vist this awesome artist and check out his other MLP:FIM pictures.