Leading up to the Dec 2007 Led Zeppelin reunion at the O2 arena in London, the members of Led Zeppelin met at the Shepperton studios, in the UK to rehearse. An MP3 version of four of the rehearsal songs has leaked online at The Big O Zine.
The four songs are Good Times, Bad Times, For Your Life, Since I've Been Loving You and Rock and Roll. On the Led Zeppelin newsgroup FBO, commentators have been mixed on the release. Some have commented on Jimmy Page's superior playing, John Paul Jones sounding strong. Others have noted that Robert Plant is not giving 100% (not uncommon for singers at rehearsal), and that Good Times, Bad Times and Rock and Roll are being played a key lower than originally recorded. For my money, all those comments are correct, but would add I don't like Jimmy Page's tone, especially on Good Times, Bad Times.
However, this is historically interesting and important archival material. Listen also for the harmony vocals on the chorus Good Times, Bad Times - Jason Bonham, perhaps?
The songs are currently only available on MP3, but are still well worth a listen for any Led Zeppelin fan.