I thought coldplay would be impossible to cover especially after seeing Avril Lavigne butcher "The Scientist". Recently I have found an impossibly brilliant cover artist named Valerio Carboni. He listens to the song and makes his own arrangement on the piano. Just take a few minutes to listen to these songs, this guy deserves a lot of respect. Rewind is my favorite of his cover pieces.
Fix You (cover)-
Rewind by Paolo Nutini (cover)-