Libxslt is a C library for GNOME which allows developers to work with XSLT. It is based on libxml for XML parsing, tree manipulation, and XPath support. Also included is 'xsltproc', a command line XSLT processor. The library is written in plain C, making as few assumptions as possible, and sticking closely to ANSI C/POSIX for easy embedding. It should work on Linux, Unix, and Windows. Though not designed primarily with performances in mind, libxslt seems to be a relatively fast processor. It also include full support for the EXSLT set of extension functions as well as some common extensions present in other XSLT engines.
Libxml2 is the XML C library developed for the Gnome project. The library code is portable (to Linux, Unix, Windows, embedded systems, etc.) and modular; most of the extensions can be compiled out. Libxml2 implements a number of existing standards related to markup languages, including the XML standard, Namespaces in XML, XML Base, Relax NG, RFC 2396, XPath, XPointer, HTML4, XInclude, SGML Catalogs, and XML Catalogs. In most cases, libxml tries to implement the specifications in a relatively strict way. To some extent, it provides support for the following specifications, but doesn't claim to implement them: DOM, FTP client, HTTP client, and SAX2. Support for W3C XML Schemas is in progress. It includes xmllint, a command line XML validator.
itools is a collection of Python libraries which provides a wide range of capabilities, including an abstraction over directory and file resources, a search engine, type marshallers, datatype schemas, i18n support, URI handlers, a Web programming interface, a workflow interface, and support for data formats such as (X)HTML, XML, iCalendar, RSS 2.0, and XLIFF.
boodebr is a collection of Python modules from boodebr.org. boodebr.ion provides JSON and XML serialization with a common API (internal and external). boodebr.config provides flexible configuration file handling (similar to INI files, but using JSON/XML with full object pickling).
WikklyText is a Python-based wiki and modular library for creating custom wikitext rendering applications. Its wikitext engine is compatible with the TiddlyWiki markup language. It functions equally well as a wiki-on-a-stick or as a multiuser wiki behind Apache. It includes a Drupal plugin as well.
python-musicbrainz2 provides simple, object oriented access to the MusicBrainz Web service. The MusicBrainz Project (see http://musicbrainz.org) provides music metadata maintained by its large and constantly growing user community. This package helps you to write CD ripper applications, taggers, and media players by giving easy access to music metadata.