What is the greatest live performance by a rock artists and why?

Easy….
Foo Fighters in Sydney December 2005.
Because they sounded brilliant, put on a fantastic show not only on stage but with lasors also. Dave (singer) involved the audience & made the show unique from any other of their tour shows. If they come back to Australia, I will most definatly be going to see them again!
They played for two hours playing all the songs off their latest album, In Your Honor (2 disk album) then came back for an encore of their songs from previous albums dating back to 1996. The drummer promoted his new songs by singing them while Dave played the drums. It was also the bass players birthday so we kinda got lucky there! We (the audience) sang happy birthday to him while the boys from the band rocked hard with their instruments.
It was by far the best concert I’ve been to!!
Bloody awesome mate!

3 Doors Down, i don’t remember when it was…but it was in Billings, Montana when i went to see them. The tickets were free so i said “what the hell?” They sound so perfect i swore they were just pretending to play and sing….it sounded like the CD exactly.