Ciscoasa.vim is a project mainly written in Vim Script, it's free.
Cisco ASA firewall syntax highlighting
This is a mirror of http://www.vim.org/scripts/script.php?script_id=3055
Cisco ASA - Adaptive Security Appliance
This syntax file will highlight the many common structures of the configuration. It helps to prevent some obvious mistakes and makes the result a lot more readable.
The syntax is far from complete, but many important parts have been implemented.