Good luck finding a good one, man....audience tapes suck!!!j
edit- That was sarcastic as hell...
It is true that audience recordings can pick up more ambient noise than what you want (talking, yelling, whatever), but given the right placement (and conditions, of course) you can produce some hair raising results.
There is a plethora of live recordings at
www.archive.org under the Live Music Archive. There are mp3's as well as higher resolution recordings. If the information is given for the performance, you will possibly see any(or more) of the following: source/mics/preamp/AD/recorder/mic configuration and placement.
Some recordings make you want to leave the room. Some keep you from leaving.