Berkeley DB XML is a native XML database engine for use within your product. Made available as a C++ library with language bindings for Java, Perl, Python, PHP, and Tcl, it integrates directly into your application (it is not a standalone database server). It provides XQuery access into a database of document containers. XML documents are stored and indexed in their native format using Berkeley DB as the transactional database engine.
BitNami RubyStack provides a fast, easy way to develop and deploy Ruby on Rails applications. It includes Ruby, Subversion, MySQL, SQLite, ImageMagick, and several Ruby Gems, and will optionally install Apache 2.2 with rewrite and proxy support. It supports Windows, Linux, and OS X, so you can share the same Rails environment on multiple platforms.
Facter is a simple cross-platform library for determining basic facts about an operating system, like the operating system name, IP address, or MAC address. It supports multiple mechanisms for resolving a given fact, and these mechanisms can be restricted to only working on specified operating systems or operating system releases.
Rant is a flexible build tool. The equivalent to a Makefile for make is the Rantfile, which is actually a valid Ruby script that is read in by the rant command. It currently features automated testing, packaging, and RDoc generation for Ruby applications and libraries, creation of gzipped tar and zip archives on all supported platforms without additional software, recognition of file changes based on MD5 checksums, dependency checking for C/C++ source files (makedepend is not required), and more. It can generate a script tailored to the needs of a specific project, which can be used instead of an Rant installation so that users aren't dependent on Rant.
Tioga is a Ruby library for creating figures and plots with high quality text and graphics in PDF format. Text is processed directly by TeX (not an emulation), and the graphics covers a broad range of PDF features including images, curves, clipping, and transparency. Tioga is relatively easy to use, complete, and well documented.