[fdsary]

I think Duplicity (http://duplicity.nongnu.org) is what you're looking for. For Ubuntu I know there's a nice GUI that anyone who can use a computer can set up. For other platforms I think cli is the only way, but someone could just write a QT/Cocoa wrapper around it.

[elithrar]

Duply (http://duply.net/) is a wrapper around Duplicity, and there's a GUI front-end called Deja Dup too: http://live.gnome.org/DejaDup/Screenshots

I use Duply to schedule incremental backups of my server logs to S3 (write only) and then have S3 expire them after 60 days. Works great.