Interesting question. I consider S3 with a front-end like http://www.jungledisk.com/
Does anybody have any experience with that?
Does anybody have any experience with that?
Another big plus is that you can run an unlimited number of instances across any number of machines after paying a one time fee of $25.
Jungledisk Plus gives you the option to view files online - so it's a backup + online viewing option (since it uses Amazon S3 and is already online).
It looks like the "Plus" service's block-level access and transfer resume would pay for itself pretty quickly with a reasonable volume of data ($1/month vs 0.10 or 0.18 per GB up/down), besides being worth it for $1 anyway.