Dr. J's Poor Man DNS Anomaly Detection using Bro

Dr. Johannes Ullrich of the SANS Internet Storm Center posted a great DNS Anomaly Detection script based on the query logs coming from his DNS server. We can do the same thing with Bro's dns.log (where Bro captures all the DNS queries it sees on the network):
http://code.google.com/p/security-onion/wiki/DNSAnomalyDetection