Amethyst started as a port of Infobot to POE, continuing as a generic bot core with the ability to handle multiple connections using different protocols (not necessarily IRC) and soft route the incoming messages through a number of processing centres. One of these processing centres contains much of the original Infobot core.
The SQLB Perl module provide a simple API to interface SQL Load Balancer within Perl scripts. It allows you to interface your scripts with Oracle, MySQL, or PostgreSQL easily and efficiently. You can change your database type easily, the only changes required in your scripts being to queries with database-specific options.
OpenIsis provides a library and tools to access CDS/ISIS databases, which are mostly used for bibliographic data (ISO2709, Z39.50) but also well suited for other catalogues due to the very flexible indexing mechanism. Based on a C library, there are also bindings for Perl and Java (Tcl to come).
WebTools is "system" of multiple modules and libraries. Along with template engine capabilities, it features session management, global variables support, cookies support, and various database interfaces. It also features a pure Perl mail client, categories management, form checking, and libraries such as a CGI-based downloading library, HTML parsers, and a library that makes PHP functions available to Perl for ease of development.
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).
TCB::Library is a DBIx::Frame object written to keep track of library books at the TCB Group at UIUC. It provides a Web interface for adding books to the library, for users to check out and return them, and for reminder messages to be sent out periodically to list what books are checked out. This is actually a fairly basic function of research groups, but doesn't have a standard software package.
TapeChanger::MTX is a module to manipulate a tape library using the 'mtx' tape library program. It is meant to work with a simple shell/Perl script to load and unload tapes as appropriate, and to provide an interface for more complicated programs to do the same. It comes with a few basic scripts to use much of the functionality of the module.