TokenLock monitors your phone, any bluetooth device, any USB device or your Apple IR Remote. When they are disconnected or out of range it locks your Mac. It can also unlock your Mac when they are reconnected or come back in range.

Unlike competitors, TokenLock can also unlock your screen saver or automatically enter your password when your Mac wakes from sleep - so long as your device is connected or in range.

Other features not available anywhere else:
Run any App, Shell script or AppleScript when locking or unlocking. The possibilities are limitless - log out of your IM client. Stop music playback. Send yourself a message and more.

Safe Networks: Avoid locking on certain WiFi networks
Sleep Aware: When TokenLock is locked it can allow both Screen Saver and sleeping.
Customizable lock screens, messages and backgrounds.

USB Options:
Check device serial numbers for lock/unlock.
Active checking when starting up to make sure the device is present, otherwise lock the computer.
USB Grace period gives you time to quickly swap USB ports if necessary.
Relock will re-lock if someone manually unlocked your computer without inserting the USB device.

Compatibility: OS X 10.6 or later, 64-bit processor

More info - https://itunes.apple.com/us/app/tokenlock/id402433482?mt=12