Metarw-git is a project mainly written in Vim Script, it's free.
metarw scheme: git
This is a mirror of http://www.vim.org/scripts/script.php?script_id=2336
metarw-git is a scheme for |metarw| to read or to browse various objects in a git repository with fakepaths like "git:HEAD~3:src/ui.c".
Note that this scheme just supports reading from an object. Writing to an object is not supported.
Requirements:
Latest version: http://github.com/kana/vim-metarw-git
Document in HTML format: http://kana.github.com/config/vim/metarw-git.html