There's no site that lists them, you have to do some research and even then there's always a chance the record isn't accurate as a boxer could throw away his card and start a new amateur 'career' from scratch if he so wanted and quite a few bouts might not even be listed.
go to nsb's front page to view all threads and use the search tool and type in "amatuer records". since i've been here i've seen plenty.
here's some of i found.
http://www.boxingscene.com/forums/showthread.php?t=514385
http://www.boxingscene.com/forums/showthread.php?t=503260