Ttags is a project mainly written in Vim Script, it's free.
Tag list browser (List, filter, preview, jump to tags)
This is a mirror of http://www.vim.org/scripts/script.php?script_id=2018
:TTags [KIND] [TAGS_RX] [FILE_RX] In order to match any kind/rx, use . E.g. TTags * _foo.vim$
Features:
You can use :echo keys(ttags#Kinds())