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.
doclifter helps with lifting documents with nroff markup to XML-DocBook. Lifting documents from presentation level to semantic level is hard, and a really good job requires human polishing. This tool aims to do everything that can be mechanized, and to preserve any troff-level information that might have structural implications in XML comments. TBL tables are translated into DocBook table markup, PIC into SVG, and EQN into MathML (relying on pic2svg and GNU eqn for the last two).
Template Data Interface (TDI, /ʹtedɪ/) is a markup templating system written in Python with (optional but recommended) speedup code written in C. Unlike most templating systems, TDI does not invent its own language to provide functionality. Instead, you simply mark the nodes you want to manipulate within the template document. The template is parsed, and the marked nodes are presented to your Python code, where they can be modified in any way you want.
LyX is a document processor that encourages an approach to writing based on the structure of your documents, not their appearance. It is intended for people people who write and want their writing to look great without tinkering with formatting details, font attributes, or page boundaries. On screen, it looks like any word processor, but it uses the TeX engine for printed output and producing richly cross-referenced PDFs. It is stable and fully featured.
pyPEG is a quick and easy solution for creating a parser in Python programs. pyPEG uses a PEG language in Python data structures to parse, so it can be used dynamically to parse nearly every context free language. The output is a plain Python data structure called pyAST, or, as an alternative, XML.
XIST is an extensible HTML and XML generator. It is also an XML parser with a very simple and Python-esque tree API. Every XML element type corresponds to a Python class, and these Python classes provide a conversion method to transform the XML tree (e.g. into HTML). XIST can be considered 'object-oriented XSLT'. XIST also includes a cross-platform templating language, Oracle utilities, and various other tools.