You could have a look at Owncloud (http://owncloud.org http://owncloud.org). I played around with it a couple of days ago and seems to be quite powerful. It act

You could have a look at Owncloud (http://owncloud.org http://owncloud.org). I played around with it a couple of days ago and seems to be quite powerful. It acts very much like Dropbox and can be installed on any web server that supports PHP.