Coro is a package providing both low-level coroutines as well as a high-level multitasking abstraction on top of Perl. It allows you to parallelize LWP and other network protocols with ease. Unlike the so-called "Perl threads/fork emulation", they provide a real shared address space (like real threads) without the associated race conditions and performance loss, while maintaining a very low memory overhead (2-3kb/coroutine). The package comes with examples and many supporting modules.
IO::AIO implements fully asynchronous I/O (not non-blocking I/O) that lets your program stay in control and interactive even when doing heavy disk (or other) I/O. It provides asynchronous versions of read(), write(), open(), stat(), unlink(), rename(), utime(), readlink(), and most other standard syscalls as well as interfaces to sendfile(), readahead(), and other esoteric syscalls, complete with emulation on systems that don't support them. It also offers convenience functions to load whole files and more. It fits naturally into any event loop model, supports 9 priorities and request grouping.
Net::Amazon::S3::Tools is a set of command line tools for Amazon AWS S3. It allows the user to manipulate an S3 account, set and display ACLs, list and create and delete buckets, list and get and put and delete items. All these operations are invoked from the command line in a way that is similar to manipulating files.
Libev is a high-performance event loop for C (with optional and separate interfaces for C++ and Perl), featuring support for I/O, timers (relative and absolute, cron-like ones), signals, process status changes, and other types of events. It has both a fast native API and libevent emulation to support programs written using the libevent API. Differences to libevent include higher speed, simpler design, more features, less memory usage, embedability, and no arbitrary limits. libev supports epoll, kqueue, Solaris event ports, poll, and select.
ExifTool is a platform-independent Perl library plus a command line application for reading, writing, and editing meta-information in image, audio, and video files. It supports many different types of metadata including EXIF, GPS, IPTC, XMP, JFIF, GeoTIFF, ICC Profile, Photoshop IRB, FlashPix, AFCP, and ID3, as well as the maker notes of many digital cameras.
VoiceXML::Client is a library that provides Perl programs with the ability to act as a user agent that fetches Voice Extensible Markup Language (VoiceXML) documents, parses them, and then executes the instructions therein by playing prompts and collecting user DTMF input/voice recordings through a handle to some type of telephone or other device interface. VoiceXML::Client's focus is on the client side. The XML documents are generated by a distinct process of your choice, unrelated to the library.
Perl::Critic is an extensible framework for creating and applying coding standards to Perl source code. Essentially, it is a static source code analysis engine. It is distributed with a number of Perl::Critic::Policy modules that attempt to enforce various coding guidelines. Most Policy modules are based on Damian Conway's book Perl Best Practices. However, Perl::Critic is not limited to PBP, and will even support Policies that contradict Conway. You can enable, disable, and customize those Polices through the Perl::Critic interface. You can also create new Policy modules that suit your own tastes.