autofwd is an automated firewalling daemon intended to block hosts performing unwanted acts. While it was designed to be used to thwart hosts running dictionary attacks on logins (of any service), it can be used for just about anything. The external commands it runs are configurable, allowing you to take additional actions against offending hosts such as running an nmap OS fingerprint before firewalling, or just silently logging the event.
bondctl is a utility that allows you create, configure, and destroy bonding interfaces on Linux. It duplicates all the functionality of ifenslave with additional capabilities, including the ability to configure parameters on a per-master basis. It's a simple script that works off of sysfs and is compatible with the busybox implementation of ash, making it suitable for initramfs environments.
Class::EHierarchy is intended for use as a base class where hierarchally ordered objects are desired. This class allows you to define a parent - child relationship between objects and ensures an orderly destruction of objects according to that relationship, instead of perl's reverse order destruction sequence based on reference counting.
The Paranoid modules provide a number of routines that are intended for use in strict and taint-safe scripts. The modules cover a variety of tasks from command-line argument parsing to process and network management. All of the modules use a debug trace framework for diagnostic output that is easily used and extended for application code as well.