The upcoming version of OpenSSH (4.8p1 for the GNU/Linux port) features a new configuration option : ChrootDirectory. This has been made possible by a new SFTP subsystem statically linked to sshd.
rsnapshot is a filesystem backup utility based on rsync. Using rsnapshot, it is possible to take snapshots of your filesystems at different points in time. Using hard links, rsnapshot creates the illusion of multiple full backups, while only taking up the space of one full backup plus differences. When coupled with ssh, it is possible to take snapshots of remote filesystems as well.