For me personally I don't see the point.
Just because it is not a USB Host (which is what you seem to want in all those examples) you brand it as useless.
You can already get a USB Host shield if that is what you want, but this sort of processor is not well suited to host applications, much better to use the new Due.
The point about being a USB slave is that you make the arduino a peripheral to your computer to interact with it without extra drivers or intervening middle where programs. It will not be limited to the class of USB device known as HID but deviating from this will require you to write a host side driver unless you are emulating an existing device that already has a USB driver.