I have written before (see http://goo.gl/NqyQ) about Dropbox, my favorite program for synching files through the Internet and for making sure I have always backed up the latest version of critical files within seconds after creation or modification. Lots of other people seem to agree with me. Writing in the Windows Secrets newsletter, Michael Lasky heaps praises on the program:
There's no shortage of services offering file sharing, synching, and collaboration through the Internet.
But one service stands out from the rest. Dropbox is one of those simple applications that, once installed, quickly become an indispensable part of your computing process.
Having seen hundreds of PC products come and go over the years, we're not easily impressed here at Windows Secrets. But every once in a while some product — or service in this case — comes along that we soon find we can't live without. Dropbox, an online file-backup, -sharing, and -synchronization service, fits that category. We use it in the office for managing our production files, and many of us use it for our personal computing.
You can read the full article at http://windowssecrets.com/2010/10/28/01-Dropbox-File-synching-and-sharing-made-easy
Since it is published in the WINDOWS Secrets newsletter, it is written primarily for Windows users. However, almost everything mentioned applies equally to the Macintosh version.
I'd suggest paying close attention to the section entitled Reeling back through your versions history near the end of the article. Very few free backup and synchronization programs keep multiple versions in the same manner as Dropbox.