Meet the GateKeeper 4.0: a handy device that monitors your proximity and locks your computer when you are not around. It is a Bluetooth security device with a simple USB design. When you leave your computer, GateKeeper automatically locks it. It unlocks your workstation when you get back. You can use an optional two-factor authentication process to protect your data.
GateKeeper 4.0 is compatible with most USB-enabled computers. More information is available here.