Foswiki is wiki software, supporting the editing of Web pages in an ordinary Web browser by end users. What makes Foswiki special is that it supports the embedding of active and passive macros that enhance the page content (e.g. with global or dynamic information) and allow end-users to build applications that store and process data in a structured manner.
Apache::Session is a persistence framework whose purpose is to provide session management to Web developers. It is designed to work with Apache and mod_perl, but it does not depend on them and will work with any Web server. This module provides a set of classes that give the developer maximum functionality. Session data can be stored in a database, flat files, or shared memory.
Xapian is a search engine library, scalable to collections containing hundreds of millions of documents. It's written in C++ with bindings for Perl, Python, PHP, Java, Tcl, C#, Ruby, and Lua. It 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 and also a rich set of boolean query operators. Omega is a Web search application built upon the Xapian library. It can index a Web server's document tree (including HTML, PDF, OpenOffice, MS Word/Excel/Powerpoint/Works, WordPerfect, RTF, PS, etc.), or data exported from arbitrary sources (e.g. SQL databases).
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.
Podius is a flexible content management system that simplifies building of dynamic Web sites by providing clean ways to create, manage, and publish all kinds of complex content. It offers command-line and Web-based interfaces, and features an intuitive object model on top of a file-based or RDBMS-based persistence layer.
Perlbal is a Perl-based reverse proxy load balancer and Web server. It processes hundreds of millions of requests a day just for LiveJournal, Vox, and TypePad, and dozens of other "Web 2.0" applications. One of the defining things about Perlbal is that almost everything can be configured or reconfigured on the fly without needing to restart the software.
Sql2xml is a CGI program that lets you request a SQL query and convert it to JSON, CSV, XML or INI through a Web server. Sql2xml supports requests from multiple users and for multiple databases. It is intended for developers who do not have direct access to database servers due to firewalls or other restrictions.