Xsl-fo is a project mainly written in Vim Script, it's free.
xsl-fo Syntax
This is a mirror of http://www.vim.org/scripts/script.php?script_id=1441
syntax file for xsl-fo
It colors all "valid" xsl-fo elements and attributes with a set of colors making it easy to spot invalid xsl-fo constructs.
This syntax works well with other related syntaxs like xsl or xml.