I think William Shatner's version of Pulp's Common People is better than the original, Shatner's vocal inflections really make this work, he gives it this great snark, and Joe Jackson is great.
(good sound - set to Star Trek TAS scenes)
(best sound - some dude lip-syncing)
And I love Nina Gordons' cover of NWA Straight Outta Compton even though it's so wrong (or maybe right...)
^ You are the man!
Black Magic Woman - Santana (originally a Fleetwood Mac song)
I never knew that was a cover but I'm digging Mac's version right now....