Dist::Zilla builds distributions of code to be uploaded to the CPAN. In this respect, it is like ExtUtils::MakeMaker, Module::Build, or Module::Install. Unlike those tools, however, it is not also a system for installing code that has been downloaded from the CPAN. Since it's only run by authors, and is meant to be run on a repository checkout rather than on published, released code, it can do much more than those tools, and is free to make much more ludicrous demands in terms of prerequisites.
Plack is a set of tools for using the PSGI stack. It contains middleware components, a reference server, and utilities for Web application frameworks. PSGI allows Web application framework developers to only write an adapter for PSGI. End users can choose from among all the backends that support the PSGI interface: CGI, FastCGI, mod_perl, the Nginx perl module, and standalone servers.
Job-Machine is a small, but versatile system for sending jobs to a message queue and, if necessary, communicating answers back to the sender. Job::Machine uses LISTEN / NOTIFY from PostgreSQL to send signals between clients and workers. This ensures very efficient message passing, giving any worker that is awake the chance to start working immediately.
Litmus is an integrated testcase management and QA tool. It was designed to improve workflow, visibility, and turnaround time in the Mozilla QA process. Its goal is to allow users to enter software tests, run them, and view and manage the results. Along the way, users can expect to be able to do queries and reports and have access all the usual features they expect from a first-class Web application.
KiokuDB is a frontend to various data stores. Its purpose is to provide persistence for "regular" objects with as little effort as possible, without sacrificing control over how persistence is actually done, especially for objects that are harder to serialize. KiokuDB is also non-invasive: it does not use ties, AUTOLOAD, proxy objects, sv_magic, or any other type of trickery. Many features important for proper Perl space semantics are supported, including shared data, circular structures, weak references, tied structures, etc.