The following bookmarklet lets mods and 10k users see deleted messages in chat and chat transcripts. Useful for when a lot of messages have been deleting and picking through the ruins is proving tough.

javascript:$('.message:has(.deleted)').each(function(){var mid=this.id.split('-')[1];$.get('http://chat.stackexchange.com/messages/'+mid+'/history',function(data){$('#message-'+mid).css('color','red').html($(data).find('.message:eq(0)').html())})})