PowerShell
If you are not running windows 2008 and don't have PowerShell installed then go get it from Microsoft's PowerShell landing page Then in order to manage your virtual infrastructure you will need the VI Toolkit for windows.
- Powershell CMDLET list (thank you Alan Renouf for the idea and initial work)
Learning VI-Toolkit Powershell
Scripts on other locations
- Add/Remove active directory user accounts who belong to a particular security group on all ESX hosts