SpiderOak: Online backup for Windows, Mac, or Linux
SpiderOak offers 2GB of online storage space for free. If you only want to backup some Office documents, the free service might be all you ever need. But if you want to backup your photo, music, and video collections you might want to check out the subscription plans. For $10 a month you get up to 20GB of storage space. Each additional 10GB will cost you $5. Or you can signup for "forever" storage. A one time $500 payment will get you 20GB for as long as SpiderOak is in business, while $1000 will get you 100GB.
The service costs a bit more than Carbonite, which offers unlimited storage for $50 annually or Mozy, which costs about $60 per year for unlimited storage. But the interface is dead simple to use, and SpiderOak is one of the few online storage solutions to offer a Linux client. Jungle Disk, a backup application designed to work with Amazon's S3 storage service also offers a Linux client.
Note that with simplicity comes a lack of advanced features. While it's easy to select the files and folders you want to backup, the restore options leave a lot to be desired. Basically you can only restore files to a single download folder, which is fine if you just need to recover a few files at a time. But if you want to restore an entire hard drive's worth of data, you might want a bit more control over the download locations.