Easy Firewall Generator is another interesting development when it comes to iptables and netfilter. Basically, Easy Firewall Generator is a PHP webpage where you specify options and specifics of your firewall, and once all of the configurations are done, you click a button, and the webpage spits out an iptables ruleset that you can utilize.
The script contains all the basic rules, and more specific ones to contain strange patterns in packets. It also contains specific IP sysctl changes that may be needed, loads necessary modules, et cetera. The whole ruleset is also written in a redhat init.d format.
This screenshot shows one of the final stages of configuring the firewall script that is about to be created by the script. You can find more information, and a working version of the Easy Firewall Generator at http://easyfwgen.morizot.net/.