Best covers:
"All Along the Watchtower" -Jimi Hendrix.
"Baker Street" -Foo Fighters.
"Friday on my Mind" -David Bowie.
"Wonderwall" -Dave Grohl (I don't think it's been released legit, but you can download it).
"Jump" -Helsongs (very different, mind you).
"Black Night" -American Dog.
"Goodbye Blue Sky" -Snowbird.
"Whole Lotta Love" -Blonde on Blonde.
"Tiny Dancer" -Dave Grohl.
"Best of my Love" -Yvonne Elliman.
"Love Buzz" -Nirvana.
"Stone Cold Crazy" -Metallica.
"Immigrant Song" -Gotthard.
"Woodstock" -Crosby, Stills, Nash & Young (the Matthew's Southern Comfort version is just as good, too).
"Black Magic Woman" -Santana.
"See Emily Play" -David Bowie.
"Come Together" -Michael Jackson.
"Heroes" -Nico.
"Thank You" -Steven Wilson (this can be found on Youtube).
"What's New" -Linda Ronstadt (her whole album with the same title is full of covers, and they all sound utterly amazing, so I highly recommend it).
"Black Dog" -Heart.
"Blues Suede Shoes" -Motorhead.
"Eleanor Rigby" -Zoot (not the muppet, Zoot were a short-lived Aussie band).
"Tenderly" -Dr. Teeth and The Electric Mayhem. :3
"Here Comes the Night" -David Bowie.
"Rock and Roll" -Stevie Nicks.
...and now I'm trying to think of the worst...
Best Covers--Crossroads by Cream, Mr. Tambourine Man by The Byrds, This is Halloween by Marilyn Manson (Yeah, I like this version. Dun judge me. X.x), While My Guitar Gently Weeps by Floyd! :3
Hellzuz yeah! :3 I love all of those- I thought I was the only one who liked the Marilyn Manson version of that song, everyone bags it... D: