Nice reference doc on Cron timing, null-ing output etc.
#cron
WP-Crontrol « scompt.com
Pluging for harnessing the power of WP’s internal cron-ish system.
Using Rsync and SSH
This document covers using cron, ssh, and rsync to backup files over a local network or the Internet. Part of my goal is to ensure no user intervention is required when the computer is restarted (for passwords, keys, or key managers).