html2fo
- Generates valid FO documents from almost any (even badly formated) HTML file. Freeware.
- http://html2fo.sourceforge.net/

Apache's FOP Project
- Open source XSL-FO implementation; converts XSL-FO to PDF and other formats.
- http://xmlgraphics.apache.org/fop/

PassiveTeX
- 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.
- http://www.tei-c.org.uk/Software/passivetex/

XMLmind FO Converter
- An XSL-FO to RTF converter [commercial, free for personal use].
- http://www.xmlmind.com/foconverter/

Antenna House XSL Formatter
- An XSL-FO processor for Windows [Commercial].
- http://www.antennahouse.com/

XML.com: Using Objects
- An article tutorial which shows how to set up XSL:fo pages.
- http://www.xml.com/pub/a/2001/01/17/xsl-fo/index.html

XSL FO Tutorial
- A learn-by-example tutorial, to facilitate reading the specification by giving a series of commented examples.
- http://www.renderx.com/tutorial.html

TeXML
- 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 usin
- http://www.alphaworks.ibm.com/tech/texml