Appnr

locks/unlocks your desktop tracking a bluetooth device

blueproximity helps you adding a little more security to your desktop.
It does so by detecting one of your bluetooth devices, most likely your
mobile phone, and keeping track of its distance. If you move away from
your computer and the distance is above a certain level (no measurement
in meters is possible) for a given time, it automatically locks your
desktop (or starts any other shell command you want).

Once away, if you return nearer than a given level for a set time your
computer unlocks magically without any interaction (or starts any other
shell command you want).