TCB::mysql is a DBIx::Frame interface to the default mysql authorization database that comes with MySQL. It was written for easy tracking (though not adding!) of information from this database within the Theoretical and Computational Biophysics Group at UIUC, using the same interface as the rest of the databases used there. It provides a basic administrative interface for adding, modifying, or deleting this information. It isn't as full-featured as some of the scripts that come with the package, but it still works pretty well.
TapeChanger::MTX is a module to manipulate a tape library using the 'mtx' tape library program. It is meant to work with a simple shell/Perl script to load and unload tapes as appropriate, and to provide an interface for more complicated programs to do the same. It comes with a few basic scripts to use much of the functionality of the module.
The Tcl extension provides a small but complete interface into libtcl and any other Tcl-based library for Perl programmers. It lets you create Tcl interpreters (as Perl 5 objects), bind in commands to them (either Perl subroutines or C functions dynamically loaded with the DynaLoader extension), and execute Tcl code in those interpreters.
Test::Class provides a simple way of creating classes and objects to test your Perl code in an xUnit style. Built using Test::Builder, it was designed to work with other Test::Builder-based modules. You can easily package your tests as classes/modules rather than *.t scripts. This simplifies reuse, documentation, and distribution, encourages refactoring, and allows tests to be extended by inheritance.
Test::Cmd provides a framework for portable, automated testing of executable commands and scripts (in any language, not just Perl), especially those that interact with the file system. In addition to running tests and evaluating conditions, the Test::Cmd module manages and cleans up temporary workspace directories, and provides methods for creating files and directories from in-line data (here-documents).