Did an OS upgrade on one machine. A couple days later, a conflict between the new OS, the SATA driver, and one other program, when it was told to defragment the system partition resulted in pretty much a DBAN-ing  of the system partition. Even running strings against /dev/hda resulted in nada... (and that is really bad.)
Thankfully, I back up my machines often (2-3x a day). So, I made a disaster recovery CD, booted it on the dead machine, told the backup server to do a restore over the LAN, wandered off, and had the machine fully restored from a dead state in about two hours.
Now, this morning, my phone crashed. Did a soft reboot, and it hung at the OS screen. Hard reset time. Copied a backup executable  to the phone's mini-SD card, ran it, told it to restore everything, and the phone was back up and running.
Moral of the story: Its really nice to have a backup system in place. Its also really nice to find that the backup system works when its needed.
: dban.sourceforge.net -- Derik's Boot and Nuke. A great tool to run on machines to make sure nothing is on any of their hard disks before moving them to another department in a company.
: SPB backup stores its backup files in .exe format, so one can just copy them to a phone and run it, restoring what is needed.