An XSL-FO processor for Windows [Commercial].

Generates valid FO documents from almost any (even badly formated) HTML file. Freeware.

PassiveTeX is a library of TeX macros which can be used to process an XML document which results from an XSL transformation to formatting objects. PassiveTeX provides a rapid development environment for experimenting with XSL FO.

Although this is not an XSL-FO tool, it is used in typesetting. Given that it was posted in 1998, it would probably be overtaken by XSL-FO now. The materials also include an example of MathML markup transformed into TeXML, with PostScript generated using TeX.

An article tutorial which shows how to set up XSL:fo pages.

An XSL-FO to RTF converter [commercial, free for personal use].

A learn-by-example tutorial, to facilitate reading the specification by giving a series of commented examples.