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.
Search::Xapian is a Perl XS frontend to the Xapian C++ search library. It is a fairly complete wrapper: most features of the Xapian library are made available for use from Perl. Xapian is a highly adaptable toolkit that allows developers to easily add advanced indexing and search facilities to their own applications. It supports the Probabilistic Information Retrieval model as well as a rich set of boolean query operators. It's fast and scalable to hundreds of millions of documents.
Autodia is a command line Perl application that generates UML class diagrams from source code, SQL, and database connections. It supports multiple programming languages including SQL, and can output images (using GraphViz/VCG/SpringGraph), Dia XML and Umbrello XML, or custom formats using templates.
Catalyst is a Web application framework for Perl. It is based on Maypole, and adds many features from Ruby on Rails, Struts, Spring, and Tomcat. The development philosophy focuses on Don't Repeat Yourself, Lego-like components, Code Generation, and very strong testability. It supports a number of plugins, models, views, and controllers.
PerlPad is a Cocoa application that lets users run Perl from other apps using System Services. Perl code can be evaluated from any TextInput, current selection can be processed with some Perl code (nice to test some regex), or users can process the system pasteboard in the same way. Buttons can even be defined for favorite Perl snippets along with add-on services for the service menu. The Perl environment provided is persistent (as long as the app stays alive), allowing data to be shared between invocations and custom Perl modules to be loaded.
Zoidberg (a.k.a. zoid) provides a modular Perl shell written, configured, and operated entirely in Perl. It aspires to be a fully operational login shell with all the features one normally expects. But it also gives direct access to Perl objects and data structures from the command line, and allows you to run Perl code within the scope of your command line.