rsnapgraph is a utility that will analyze the snapshot backups created by
rsnapshot (http://www.rsnapshot.org), and produce two graphs showing file and
disk space changes over time.
* The rsnapshot-files.png graph shows the number of files created and deleted
between each snapshot, as well as a running graph showing the total number
of files in each snapshot.
* The rsnapshot-size graph shows the amount of disk space being freed or used
by each snapshot, as well as a running graph showing the total amount of
disk space used by each snapshot.

It's useful to know whether the snapshots are very volatile, and if so, which
directories are changing. If disk space is tight, then this can help identify
directories within each snapshot which can be removed from the snapshot to
save space. Plus the graphs are pretty.