Not a fan of Metallica but they did a darn fine job with Turn The Page (Bob Seger).
I agree Dayton, that cover completely rocked!!!
My favorite is a remake of the Pearl Jam song of "Black" that was on their debut album. Aaron Lewis who is the lead singer of the band Staind, put out an acoustical version of this song that takes it into an entirely different direction. This version really strips down the song, and emphasizes the heartbreaking words of the lyrics. A song about lost love, that we have all shared at least once in our life, if not more.
Because it gives the song such a different "identity" it is my personal favorite remake. See link below.
http://www.youtube.com/watch?v=sumiU0u2J9s