Yeah, that Hurt cover by Johnny Cash is great. Johnny was never shy about doing others; music if he liked it, but late in life he seemed to go on a binge. I love this cover of U2's One ... Johnny seems 100 years old, but was shortly before his death at 71.
http://www.youtube.com/watch?v=h8d_8fM6PQc
And speaking of All Along The Watchtower, Neil Young loves that song, and has done it a lot. Here is at Farm Aid 1994 with Willie. Funny, but first time I heard Neil do it I was like, "Wow, Neil is covering Jimi". Then, "Noi, even better, Neil covering Jimi covering Dylan" ...