The Unreal Machines name came up as a play on words, taking physical machines and turning them into virtual machines. The machines now being nothing but 1's and 0's, are no longer physical, don't physically exist... yup, you get it :). 

UnrealMachines is a directory of ready to tun, turk-key operating systems and applications which have been authored with everything needed in one bundle of software. Simply download the software, install from ISO file or as a preconfigured ready to run guest.

Virtualization allows one computer to act as a host, essentially allowing you to run multiple computers on one physical machine. The host allows it's resources to be shared across multiple environments.
These environments are known as Virtual servers and can consist of multiple operating systems, multiple applications, either locally or in remote locations. Operating systems include Linux, Windows (tm), and others. The obvious benefits are that of saving energy savings and lowering capital costs by more efficiently using hardware resources.

Added benefits include high availability, better desktop management, increased security, improved disaster recovery and simple management of multiple operating systems from one console.

There are a great number of resources on the Internet which can better explain how you can benefit from Virtualization techniques to maximize your hardware and resources.

If you know an author who wants to let people know about that cool project, let them know about this site. If you are an author, by all means, post your work so that everyone can know about your Unreal Machine!