Control multiple terminals open on different servers to perform administration
tasks, for example multiple hosts requiring the same config within a cluster.
Not limited to use with clusters, however.

The Perl MIME-Interface

The Perl MIME-Interface

Powerful date parsing, arithmetic and other manipulation

Produce RFC 8822 date strings

The Perl Email Validator

This is an autoloadable interface module for libgd, a popular library
for creating and manipulating PNG files. With this library you can
create PNG images on the fly or modify existing files.

This version of GD no longer supports GIF output because of threats
from the legal department at Unisys. Source code that calls
$image->gif will have to be changed to call either $image->jpg or
$image->png to output in JPEG or PNG formats. The last version of GD
that supported GIF output was version 1.19.

Determine the size of images in several common formats in Perl

pigz, which stands for parallel implementation of gzip, is a fully functional replacement for gzip that exploits multiple processors and multiple cores to the hilt when compressing data. pigz was written by Mark Adler, and uses the zlib and pthread libraries.

The Perl XML-Parser

The Perl XML-Interface