Tainted Love by Soft Cell-- yes they weren't the original, though theirs is often (if not usually) considered a different version because of changing "girl" to "boy", "play" to "pray", and the last line or two being almost completely different, and Hurt done by Johnny Cash, originally by Nine Inch Nails-- both better than the original IMHO. Oh and Dancing Queen by Britney Spears for obvious reasons.