Great if you have some .fo or .fop files you want to transform into HTML.

The attachment is a freeware XSL file from RenderX that can be used to transform XSL-FO into HTML. Use it with Apache Xalan (for Java) like this:

java org.apache.xalan.xslt.Process -XML -in file.fo -xsl fo2html.xsl -out file.html

Of course, as XSL-FO is page centric, the resulting HTML will NOT be chopped up into pages, but only one long page. But it might be useful just to see the contents of the XSL-FO file like HTML, instead of creating PDF‘s via Apache FOP (which btw has a xalan.bat, very similar to the one I created :-).