The Cure's version of Purple Haze:
https://www.youtube.com/watch?v=cLGlDQRYJ9MJust love the hypnotic vibe of it. What's funny is that it not only sounds nothing like the original, but it doesn't really sound like typical Cure, either.
LTE's version of Rhapsody in Blue
Jimi Hendrix's version of All Along the Watchtower
Iron Maiden's version of That Girl
Jolly's version of You Belong With Me
Blue Man Group's version of One of These Days (altho I guess it's not that different from the original)
half of Zeppelin's first few of albums!