I am finally backing my life (and my company's data) offsite with Amazon S3. I have been diving into this full on and it's quite cool. It took me way way too long to get it all set up. Nearly 4 hours to get a 7 line shell script in a cron job, due to a serious of yak-shaving events
In any case, it was basically easy with s3sync (the Ruby version, I believe the Perl version is abandoned...) Here is a decent link on getting it done. I actually used Marcel Molina's s3sh shell program a bit, simply because the error messages it dumped were vastly better than the HTTP 403s I was getting from s3sync. I just didn't find s3sh as "scriptable" due to my lack of shell scripting expertise at the moment. I am just glad I have a place to practice.
It's definitely worth reading a bit on the main AWS site about S3 before diving in. I wasted quite a bit of time due to not understanding the flexibility of the key/bucket system's handling of directories. And the minor bit about buckets having to be unique across all users.