Pentadactyl ftdetect, ftplugin, and syntax files, consumable by Vundle
The excellent Pentadactyl plugin for Firefox already provides syntax files and such. You can even generate them right from FF with the mkvimruntime command. However, that creates the directories right in your vim path.
I use Vundle, which encourages a cleaner approach. You can use this repo to keep the pentadactyl-specific stuff in a separate bundle. Just add this to your .vimrc:
Bundle 'dogrover/vim-pentadactyl'
This is, by no means, an official repository. I'll keep it up to date as needed, until the selfless maintainers of pentadactyl see fit to create their own.