iwilldiffer is a vim plugin that shows you git diff add/mod/del lines in the gutter.
You need git, diff, python (2.6+), vim.
Install the plugin (TODO: describe the magic which is installing vim plugins)
You might want the following in your .vimrc:
let g:iwilldiffer_check_on_open=1 let g:iwilldiffer_check_on_save=1