GNA Frontdesk is a groupware application designed for customer support and bug tracking. People e-mail their messages into a threaded central repository which may be accessed via the web. The Frontdesk groupware system is written entirely in Perl and currently runs under any platform that supports perl.
GNU Make examines the timestamps on a set of interdependent files, and, if necessary, issues commands to bring them up-to-date. The user creates a makefile describing the files, their relationships, and the commands to run. Most often make is used to rebuild libraries and programs when their sources are changed, but it can be used for any situation where one set of files needs to be generated from another set.
Sather is an object oriented language designed to be simple, efficient, safe, flexible and non-proprietary. One way of placing it in the "space of languages" is to say that it aims to be as efficient as C, C++, or Fortran, as elegant as and safer than Eiffel, and support higher-order functions and iteration abstraction as well as Common Lisp, CLU or Scheme.
Cook is a tool for constructing files. It is given a set of files to create, and recipes of how to create them. In any non-trivial program there will be prerequisites to performing the actions necessary to creating any file, such as include files. Cook provides a mechanism to define these. When a program is being developed or maintained, the programmer will typically change one file of several which comprise the program. Cook examines the last-modified times of the files to see when the prerequisites of a file have changed, implying that the file needs to be recreated as it is logically out of date.
This is a handy little library which provides a packet filtering mechanism based on the BSD packet filter (BPF). Most notably, tcpdump needs this to work, and there is also a perl module (still in beta) which can use this as well. In plain english, if you want to write your own network traffic analyzer, this is the place to start.
Perl is a high-level, general-purpose programming language that makes easy things easy and hard things possible. It is optimized for scanning arbitrary text files and system administration. It has built-in extended regular expression matching and replacement, a dataflow mechanism to improve security with setuid scripts and is extensible via modules that can interface to C libraries.