A script to set up and deploy django servers. Hat tip rob.
An out of date guide on how to setup scponly and a chrooted scponly. It includes info on a bug (dev/null) which is now fixed, but otherwise it generally applies.
Keychain is a front end for ssh-agent which sets up one ssh-agent session per machine reboot. Useful for unattended backups, and so on, as the key passwords need only be provided once per reboot.
rsnapshot is a perl utility that creates (illusory) filesystem snapshots using rsync and hardlinks (to save space). Every time a file is changed, a new copy is created, otherwise a hard link is used. It works hourly, daily or monthly.
Useful article on how to backup and restore MySQL databases. Includes example commands and a basic overview of the theory.