BitTorrent Sync automatically syncs files between computers via secure, distributed technology.
This is nothing new, I am using Dropbox everyday. But the catch line is that there is no storage limit and it is using P2P method to directly sync between computers. The only limit is the size of your hard disk. Nowadays, you should have pretty. This is not a cloud storage service, it is a piece of software.
Here is a list of some cloud storage services:
There are many more file hosting services or online backup services.