Algorithm::Diff is a Perl module for computing the difference between two files, two strings, or any other two lists of things. It uses an intelligent algorithm similar to (or identical to) the one used by the Unix `diff' program. It is guaranteed to find the smallest possible set of differences.
The Archive::Zip module allows a Perl program to create, manipulate, read, and write Zip archive files without calling an external program. Members can be added, removed, extracted, replaced, rearranged, and enumerated. They can also be renamed or have their dates, comments, or other attributes queried or modified. Their data can be compressed or uncompressed as needed, and members can be created from members in existing Zip files, or from existing directories, files, or strings.
The CDDB/CDDB_get Perl module gets the CDDB info for an audio CD. The included script was intended as a demo for CDDB_get, but over time it has gained powerful features like the ability to write to a database, offline mode, HTTP mode (including proxy), saving in standard XMCD format, and writing 'lame' commands.
CfgTie is a package of Perl modules and tools. These make it easier to configure and maintain Unix computers. The idea is that just about everything in your machines environment can be operable through a single consistent interface. This is a set of tools that make many of the various configuration subsystem in your machine appear to be Perl variables of some sort.
DBIx::AnyDBD is a Perl module for developers writing cross database applications. It allows you to write "plugins" for different DBD drivers (Oracle, Sybase, etc) so that your application can do different things on different databases. It doesn't provide any compatibility layer - just an intelligent method to switch to the right class to use at runtime.