Rsync is a mirroring tool that uses a brilliant algorithm for figuring
out a small difference set between files and sending only the difference
over the link, typically using a very small bandwidth compared to e.g.,
rdist.

Rsync communicates over a lower-level protocol, such as rsh or ssh,
allowing for secure updating.

On the down side, rsync is not quite as versatile as rdist when it comes to
mirroring only part of a hierarchy, though one can possibly use a perl
wrapper to obtain the same adaptability.

Flavor: iconv
    extra dependency, for people wanting to bring files from other OSes with
    more versatile filenames.