Active Directory Recycle Bin
Windows Server 2008 R2 has a new COOL feature: Recycle Bin. Once you turn it on (one way action!) you can restore deleted objects and all their attributes are also restored, there is no longer a need to rejoin a deleted computer account or rebuild a deleted user account groups membership.
The feature has no GUI and the only way to implement it is by using PowerShell which is included by default as part of the Windows Server 2008 operating system.
Click the image to watch the video.