6. Led Zeppelin
One of the greatest bands in history are no strangers to a well anticipated reunion. The rock Gods "split up" in 1980, but have got back together no less than four times since then, for events such as Live Aid, which would suggest it's not over for Jimmy Page, Robert Plant, John Bonham and John Paul Jones just yet. Their most prolific reunion was one of the first major concerts at the O2 arena in London in 2007, which - according to the Guinness Book of World Records - held the highest demand for tickets for a one off concert, where there were no less than 20 million applicants online.