If you need free storage and don't need mobile access, LaCie Wuala's 1GB of free cloud storage may be just the ticket. The service lets you sync files between multiple PCs and share folders with friends, and it adds a welcome touch of security by encrypting all files before they leave your hard drive. It has Mac and iPhone versions, too. Pricing plans with more features and more storage start at $29 per year.
Note: This link takes you to the vendor's site, where you can download the software and register to use the service.