System Image Utility is an application for making NetBoot and other image sets to be used with Mac OS X Server. It is available as part of the server admin tools package on a disc with the server software and as a download from Apple's website. There are several third-party applications that perform similar functions.
See also
Network Image Utility
External links
Mac OS X server page Apple Server Admin Tools 10.7.5 Apple Server Admin Tools 10.6.8 Apple Server Admin Tools 10.5.7 Apple Server Admin Tools 10.4.7 Apple - Support - Downloads - Server Admin Tools (search for all versions)