This is a great little device for the not so tech savvy computer user. If you need to transfer a lot of data from one machine to another and have no idea what a cross over cable is, then check out this USB Transfer Device.
All you need to do is connect both machines via USB and then you can drag and drop between them at speeds up to 25Mb/Sec. So next time a relative calls you up asking for assistance moving their terabyte music collection to their new machine simply point them at one of these.
Available from ThinkGeek.