Allmydata: Data Storage and Peer Sharing App

Allmydata caters you unlimited free storage, provided that you share your data without limit. To use their service, you need to download a little programme, which is only available for Windows platform.

Allmydata provide various service plan. The free plan is called "10:1". For example, if you share 10GB on your hard disk, you will have 1GB on Allmydata. If you want to lift the storage ratio, you might need to join their paid services, which will soon be available.