I installed a program called JungleDisk on my Mac that enables me to back my files up over the Internet to my storage account on Amazon's Simple Storage Service (S3). This program works well and gives me assurance that my data is safely stored offsite.
Frist, I created an Amazon S3 (Simple Storage Service) account. Amazon charges $.15/month per gigabyte, plus a charge for transferring data. For 5GB of data this will cost about $20/yr. The JungleDisk program costs $20 one time and looks like a backup program: pick the files to back up once. To run a backup, just click an icon and it backs up anything that has changed; watch the progress bar.
I started my first backup on a Sunday. I had configured JungleDisk to limit its upload speed to 300KB/sec, in order to be well below half my Comcast bandwidth limit. The backup ran until Tuesday. Subsequent backups only send changed files and take much less time, usually less than an hour. The data is encrypted before it is sent.
This backup method provides storage outside the house. It doesn't replace Time Machine, which automatically backs up your Mac's hard disk every hour to a local disk drive.