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.
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.
OpenGuides is a wiki-like package for maintaining a collaborative city guide. It is written in Perl and runs as a CGI program, and uses either the MySQL, PostgreSQL, or SQLite database. It offers features over a "normal" wiki such as metadata management and a "find nearby things" function. The look and feel is highly customizable thanks to use of the Template Toolkit.
JSON::XS implements JSON for Perl. Unlike other modules, its primary goal is to encode to syntactically correct JSON and flag invalid JSON while decoding. It ensures round-trip integrity of data types while being intuitive to use. Currently being the fastest of the JSON encoders available for Perl, it supports a variety of format options, such as single-line, ASCII-only, or pretty-printed, and can be tuned for speed or memory usage. It comes with a wealth of documentation describing usage and implementation details.