rsyn is the best tool for mirroring servers and data. However, there is also mirrordir tool. As name suggest it can mirror directories and do lots of other things. It offers lots of options for die hard shell scripting fans. It can copy, mirror directory trees via a minimal set of changes, locally or over FTP, or over a secure tcp connection.

From the man page:

mirrordir copies files that are different between the directories control and mirror to the directory mirror. Files whose modification times or sizes differ are copied. File permissions, ownerships, modification times, access times (only if –access-times is used), sticky bits, and device types are duplicated. Symlinks are duplicated without any translation. Symlink modification and access times (of the symlink itself, not the file it points to) are not preserved. Hard linked files are merely copied.

mirrordir command supports strong stream cipher encryption and Diffie-Hellman key exchanges with several possible key sizes.

Install mirrordir

Use apt-get or ports system command:
$ sudo apt-get install mirrordir

mirrordir examples

Mirror ~/scripts to ~/scripts.backup:
$ mkdir ~/scripts.backup
$ mirrordir -v ~/scripts ~/scripts.backup

If you rerun mirrordir again, only the updated files are copied.

You can mirroring FTP sites:
$ mirrordir -v ftp://ftp.nixcraft.in/pub /home/backup/nixcraft.in/ftp/pub

mirrordir offers tons of option, refer mirrordir man page for more examples and options:
$ man mirrordir