Comment on FileSync

Took 5 minutes to set up. Works flawlessly, both over a network and direct to a hard drive. It's very robust and has a good variety of options that allow you to tailor the file sync to your needs (e.g. requesting the destination to mirror the folder or not, for example).
Best of all it's free, a.k.a. doesn't cost $129 - $1669 like more commercial orientated software (ahem...)

If you're even moderately able to use a computer, this is easy to use and very useful, you'll be up and running int no time.

5 stars and highly recommended.