DoTagStuff is a project mainly written in Vim Script, it's free.
Syntax Highlight based on tags
This is a mirror of http://www.vim.org/scripts/script.php?script_id=1232
Extract information from a tags file (exuberant ctags), and generate syntax highlighting scripts for functions, globals, macros, etc.
Somewhat "raw" extraction from my working environment; i.e., not particularly generic; e.g., hard-coded color settings for the various types of tokens identified (functions, macros, etc.). Easily changed, but by editing the c.vim included that is intended to go in your "after/syntax" vim directory.
Not very polished, but perhaps helpful.
For a sample of the results, see: http://castandcrew.com/~gary/DoTagStuff/
NOTE: You must include the --fields option to ctags that includes "language of source file containing tag" (i.e., "--fields=l" ; I use --fields=+Kl). It's needed so that the language type of each tag is included in the tags file. This is needed to properly form syntax groups (e.g., cStaticFunction or perlExternalFunction -- to get the "c" or "perl" parts).