Earthsite uses DropBox to share, syncronize, and backup all of our company files.  We love it because it's so easy to use and it's never failed.  We've been able to do away with out local network storage entirely with this service.  It gives us peace of mind because we now have our company files on our own computers, as well as in the 'cloud'.  We always have access to our company files from our computers, by logging into their online website, or through our iPhone apps.  It's never been easier sharing files.

If you sign up through this link, we both get an additional 250mb storage!