The dsnapshot script provides a high-level interface to the Linux Logical Volume Manager. It uses its block-level snapshot support to create directory snapshots. In contrast to block-level snapshots, directory snapshots resemble the file system layer. Thus, you can snapshot any directory that is on a logical volume without worrying about the actual logical volumes, mount points, and paths.
The pickle module implements a fundamental, but powerful algorithm for serializing and de-serializing a Python object structure. Pedit is an interactive editor for such data structures, making them handy on the command line. The code is a work in progress, but is currently useful.