Symform Offers Free Peer-to-Peer Storage
Setting up Symform is easy. Basically you tell it what you want to store in shared space, how much space you're willing to contribute (nothing, or 10GB to 150GB), and how much bandwidth to use. You can also define when transfers are to occur. One caveat: You need a relatively fast connection--64KBps upstream and 125KBps downstream. This is well within the capabilities of the average DSL or cable connection.
Unlike many online storage programs, there's no system tray app to remind you that Symform is running. It simply starts three services and stays out of the way. If you want to change settings, or see the status of your backup you simply run the setup program again.
What's not quite as easy to understand, perhaps, is that Symform is a synchronization program in its purest form. After you've set up relationship between a local and online folder to synchronize, the folders are truly and automatically synchronized. Local folders are locked, so you can't delete them from within Windows though you can delete files with them. If you get smart and rename or delete the folder using a boot disk, then it will be restored automatically next time you boot normally. Syncing continues until you remove the mapping, or uninstall the program.
Another feature of Symform is hot restore. Basically, this is a local backup that you can restore from more quickly than from online. There's also a turbo seeding feature in which you encrypt the files to a local disk, then upload them. This allows faster uploads and less CPU usage during the upload. You may also sync multiple PCs using the same account.
Obviously, Symform is relying somewhat on its users to be responsible and polite. However, data is replicated in many different locations so that it should always be available when you need it. In my limited testing, it found my data every time. Each folder being synced will have sync information placed in it, though it's in a hidden folder.