A picture is worth a thousand words.
![dropbox-revision-history Click for big version.](http://doycetesterman.com/wp/wp-content/uploads/2009/10/dropbox-revision-history2-300x187.gif)
Dropbox, by way of contrast, is worth several hundred thousand words, backed up nigh-instantly to every machine you use, with version information and restore capability that goes back to the creation of the document.
I probably already sent you an invite to this, but if I didn’t, let me know, and I will.