Most people are familiar with GPMC - the Group Policy Management Console - for administering and troubleshooting GPO's. If you're not familiar with it - download it now, you're wasting your time managing GPO's the "old" way :-)
What a lot of people don't know is that when you install GPMC, you get over 30 scripts which can be used to automate the management of GPOs. My favourite one is BackupAllGPOs.vbs - this will create a backup of all GPOs in the current domain. Any time I'm involved in an AD project, one of the first things I do is schedule this script to run nightly on a domain controller. That way I don't have to worry about AD restoration processes if someone accidentally deletes or modifies a GPO.
This script (and the others) are found in C:\Program Files\GPMC\Scripts once you install GPMC.
GPMC can be downloaded from http://www.microsoft.com/windowsserver2003/gpmc/default.mspx