Cold Chisel - Goodbye (Astrid Goodbye)......live at their peak.
Pure raw live aggression by one of the best live bands ever. Amazing this hasn't been covered by someone outside Australia.
http://www.youtube.com/watch?v=7GL_0hGBEbI
John Farnham - Every Time You Cry
Pure live with a guitar in a tv studio with a bunch of news anchors roped into singing with him. Not many people would attempt this, much less the improvisation that he does messing with the lyrics. This could have easily turned into a trainwreck.
http://www.youtube.com/watch?v=w0CAUqSMguI
John Farnham - Amazing Grace
Another one by the master. 3 voices a cappella. You don't even try this one unless you are pretty confident that you can pull it off. Starts with the amazing Vanetta Fields, then John, and finally longtime backing singer Lindsay Field joins in. Pure gospel. Not often do you find that kind of vocal talent in one band.
http://www.youtube.com/watch?v=_x6N94OEkZQ
Tina Turner - Proud Mary Live
Not so much the performance itself, but what happens. She invited a fan who had attended about 15 shows and knew all the dance moves up on stage....and he didn't miss a beat. Most people would have freaked out.
http://www.youtube.com/watch?v=CkdVUco_kzI
Johnny Adams - Stand By Me
Virtually unknown, but respected New Orleans soul singer with one of the best voices I've heard on a VERY loose live jam of the song Stand by Me....or at least that's the first minute or two of the song!
http://www.youtube.com/watch?v=FBl7ZIWnS8I