Hi,
I love great covers; they often improve on the original artist's version. One of the definitive ones is Joe Cocker's cover of the Box Tops' hit "The Letter." Leon Russell's backup piano is outstanding:
http://www.youtube.com/watchv=4RnjWLVyMps Cocker's version of Leonard Cohen's "Bird on a Wire" is also great. I much prefer listening to Jennifer Warnes' covers of Leonard Cohen songs on her album "Famous Blue Raincoat" than to Cohen himself (not to diminish Cohen's talent, but Warnes is a fine singer and Cohen isn't).
Alan