Best covers you've ever heard?

[JNightshade]

Went to a John Mayer show a few nights ago (STFU, he's a great guitarist, the tickets were free, and I use his music to get wimmenz) and he did an astonishingly good cover of the Clapton version of Crossroads. Astonishingly good.

 

[The Monkey]

Here's Cash's cover of Hurt that we were talking about earlier:
http://www.youtube.com/watch?v=SmVAWKfJ4Go

(The uploader doesn't allow embedding, just click on the link at the top of the box.)