FO Tool is a little helper application which eases the development of stylesheets for XSL-FO processing if you don’t use an XSL-FO editor, but only an XML editor. FO Tool is written in Java and can be downloaded and started through Java WebStart.
Currently the FO Tool is only available and tested on Windows. Since it uses SWT (from Eclipse) it contains platform-dependant libraries and lacking a Unix environment I cannot test right now.
Unfortunately, this tool is quite out-dated, but I find that some people are still using it. I hope I can one day create a better tool like that.