Microsoft Developer Network is running an article on XSL Transformations, along with an article on how they rebuilt their own Table of Contents with XML.

The XSLT article, adapted from a chapter of Essential XML, by Don Box and Aaron Skonnard, and John Lam, provides an introduction to using XSLT transformations to convert documents between different markup vocabularies.

The MSDN article on rebuilding their TOC demonstrates how to build a large data processor (250,000 nodes) with XML, replacing "a proprietary data structure" that "could not be reused" and had serious problems with internationalization. The article details the 'chunking' and delivery strategies they chose for shipping and maintaining information, not just the creation of a structure for storing it.