CrashPlan. The biggest advantage (which I did not see others mention) is you can have as many destinations (at the same time) as you wish. One of these can be CrashPlan's cloud storage. But you could also use S3, or even other machines. It is the "other machines" scenario that is really exciting. Backup your office machine to your home machine and vice versa. Have a good friend you trust...set each other up as backup destinations (free off-site backup!). The posibilities are limitless (actually some relatively high power of two - but you get th epoint.