Here we go:
Judas Priest- Diamonds and Rust
Van Halen- You're No Good
Iron Maiden- Crosseyed Mary
Guns N Roses- Mama Kin
Motley Crue- Helter Skelter
Tesla- Signs
Frijid Pink- House of the Rising Sun
Santana- She's Not There
Molly Hatchet- Dreams I'll Never See
It's not really a cover, but when The Rossington-Collins Band played Freebird w/o vocals, they reduced entire stadiums to tears.
(the audience used to sing it for them)
And finally, the greatest of all covers,
the most unique.
Thousands of artists do this one,
but it was only done once like this...
Jimi Hendrix- The Star Spangled Banner 
Let the Freak Flag Fly!
