A linux Driver / pam module for the pc-wireless lock usb stick plus remote unit (product name: KW-101 - thx to John Ward for telling me this).

After installation for example you can login into your local console
only by activating your usb sender unit.(That’s how i use it)
you need some basic admin skills to install this…
if you know what the kernel is - even better!

License : GPL

to buy a device look at this page
or go to this page
or visit this one
or perhaps surf to this page