The 2-1 win at Bramhall Lane against Sheff Utd, when Leon scored a late winner, rates as probably the loudest for me...other than the play-off final in Cardiff of course!
Cardiff? Loud? The atmosphere at Cardiff was shit.
In response to the thread starter, Peterborough is the loudest you are likely to ever experience and 30/10/2010 is your last chance so get down there.