Box

If you happen to use a storage service, then you’re going to need some kind of app that can sync your data with the cloud. The Box service has an app that has the same name, and which has quite a few other features than just sync.
 
With the application users can access all of the data in their storage, share the documents and files with other people, preview more than 200 types of files, and access the files while you’re in offline mode.
 
Box users also receive 10GB of free cloud storage, printing options straight from the app, file-level security controls, and support for numerous partners that allow users to annotate, e-sign, and edit files.