Undo_tags is a project mainly written in Vim Script, it's free.
small utility that lets you tag undo branches
This is a mirror of http://www.vim.org/scripts/script.php?script_id=1997
Undo branches are a very cool feature in vim7, which I recently discovered. You can navigate through the change history of the current session as long as you do not run out of undolevels.
This small plugin lets you: