I really like some of the covers Guns And Roses' did, Sympathy For The Devil, Live and Let Die, Knockin' On Heaven's Door in particular (I really hate Raw Power, but I also think no one can take on Iggy, so...)
I actually prefer Derek and The Dominos' cover of Little Wing to Jimi Hendrix's. I think the corabination of Eric, Duane and Bobby takes it to a a whole new level. Well, actually, I saw Clapton live last month with Doyle Bramhall II and it still beated Jimi's...