Allmydata is an online solution to keep your backups secured in a fast and safe form. If you don't have sufficient hard-drive space, then Allmydata is an excellent solution although it doesn't feel as safe as having your data stored locally.
The program uses a simple drag and drop interface to upload files and share them with other users. You are then offered various methods of payment depending on how much space you need to use including via credit card and Paypal. Until you need to upload data, Allmydata sits quietly in your system tray until double clicked when it bursts into life. There are a few options available to configure such as the type of file you are uploading and what type of connection you are working from.
Allmydata is an excellent online backup solution although transfer rates can be slow and it's never as safe as storing something locally.