NARC (Netfilter Automatic Rules Configurator) is a free firewalling package for Netfilter/Iptables, released under the BSD license. It attempts to simplify the setup of a firewall (stateful packet filter) via the iptables tools. It is a bash shellscript that generates (hopefully) sensible and secure rules for Netfilter based on a simple configuration file. It features quick setup via a simple configuration file, connection tracking (and fragmentation reassembly), customized logging, probe detection (TCP & UDP), and much more.
dpkg-du is a script to produce a dump of the installed size of Debian packages in du format. This is to enable ease of reuse with pre-existing scripts administrators may have to deal with 'du' format lists. For example, dpkg-du|sort -n|tail -10 will show the 10 biggest packages on your system.
mylbhelper helps dumb load balancers do their job. It monitors a local MySQL instance by periodically issuing a query. Should the query fail, a custom script, which typically would firewall off the load balancer, is executed. Likewise, when it comes back up, another script is executed. This means you can use any load balancer capable of distributing TCP traffic rather than one natively capable of talking MySQL. mylbhelper can also act solely as a monitoring daemon.