pyratemp is probably (one of) the smallest complete template-engines for Python (with about 500 LOC). It has a very small set of special syntax in the templates. This reduces complexity and the probability of bugs and lead to an easy-to-use and intuitive user-interface. It uses embedded Python-expressions (in a "sandbox"), is well documented, has full Unicode-support, and produces very good error-messages, which is very useful when creating new templates.
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).
PyBison is a sophisticated yet easy-to-use parser creation toolkit for Python that interfaces directly to Bison (yacc)-based parsers. It provides full LALR(1) grammar support, allowing for simple parsing tasks through to writing compilers for high-level languages. Parser code is automatically generated from rules within user-created Parser classes (written in Python), and then, compiled, yacc'ed and linked into a shared library, which is loaded into the running process. All this happens automatically. When the parser runs, it connects directly with the yyparse() routine, and takes event callbacks upon parse targets being reached.
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.
LEPL is a recursive descent parser library written in Python. It is based on parser combinator libraries popular in functional programming, but also exploits Python language features. Operators provide a friendly syntax, and the consistent use of generators supports full backtracking and resource management. Backtracking implies that a wide variety of grammars are supported; appropriate memoisation ensures that even left-recursive grammars terminate.
Karaoke con SMIL is a project to synchronize audio, text, and images and export the final result to SMIL, which can be played in multimedia players such as Real Player, Helix Player, Ambulant Player, etc. on several devices (computers, mobile phones, PDAs, etc.). In short, this application synchronizes the multimedia elements in a way similar to karaoke.