A command line tool that allows you to (live) analyze netfilter (iptables) log files. It provides a nice output and has features like displaying hostnames, duplicate detection... More info (+ screenshots) can be found in the pdf inside the tarball.
The Cisco Connection Analyzer will analyze a real time snap shot of your PIX/ASA connection table and tell you useful information about the conn table. It will tell you top talkers, top services..etc. Very useful in troubleshooting the firewall.