Nsis-color is a project mainly written in Vim Script, it's free.
Nullsoft install system scripts syntax highlight
This is a mirror of http://www.vim.org/scripts/script.php?script_id=267
Nullsoft install system (NSIS) scripts syntax highlight. NSIS is free and produce vary small and pretty installers. Look http://www.nullsoft.com/free/nsis/ for details.