Simple scripts that unconfigure a system so they can be used as images for virtualization, cloud, etc
What they do is:
- clear all the logs
- clean up the networking scripts, because the normally get references to the mac address in CentOS
- clean up the repository files
- in some cases create a root user
There are scripts for: CentOS 6, Debian and OpenSuse; so choose the one that can help you the most.