Cloud.com are offering 15GB of cloud storage for free.
I have been really impressed by the cloud.com system. There are clients for android, IOS Mac, Windows and Linux.
I am using the client to sync between Windows, Android and Linux and it is by far the easiest cloud storage implementation so far with Dropbox a close second although offering less space.
The installation and setup up is easy and configuration is simple. You will get 15GB of storage free and if you sign up from here you will get a 5GB increase, giving 20GB of space free.