Sorry for being ignorant but.. what's DropBox exactly?
Dropbox is a file hosting service operated by Dropbox, Inc. that offers cloud storage, file synchronization, and client software.
Dropbox, Inc. was founded in 2007 by MIT graduates Drew Houston and Arash Ferdowsi, as a Y Combinator startup company.
Dropbox's basic service follows the freemium business model. In 2011 Dropbox announced a new service, "Dropbox for Teams", marketed to businesses and other groups.
Dropbox provides client software for Microsoft Windows, Mac OS X, Linux, Android, iOS, and BlackBerry OS, and web browsers.
http://en.wikipedia.org/wiki/Dropbox_(service)