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).
The DBI module enables your Perl applications to access multiple database types transparently. You can connect to MySQL, MSSQL, Oracle, Informix, Sybase, ODBC, and other database systems without having to know the different underlying interfaces of each. The API defined by DBI will work on all these database types and many more. You can connect to multiple databases of different types at the same time and easily move data between them.
wad2svg takes a level file for the computer game Doom, and draws a 2D map of the level as an SVG (Scalable Vector Graphic) file. This can then be edited and/or converted to a raster image using a suitable vector graphics programs. wad2svg can also draw the node tree of a Doom level, and is designed to be extended to draw other aspects of the level.
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.
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.