Open source application Blue Lock monitors the proximity of your Bluetooth phone or device and automatically locks your computer whenever it’s out of range (e.g., you’ve walked away from your computer). The usefulness will depend on the strength of your Bluetooth devices, since it’s not really going to do its job if you’ve got a strong signal and receiver that keeps a connection from across the office. But if it works well with your Bluetooth devices, Blue Lock provides a simple way to keep your computer secure when you step away for a few seconds but forget to hit Win-L to lock your workstation. Blue Lock is free, Windows only.

Unfortunately, despite the fact that my phone DOES pair with my laptop, I couldn’t get Bluelock to work. I currently have an HTC Touch (Sprint Touch aka HTC Vogue). Bluelock flat out won’t find my phone. Ce la vi… maybe it’ll work for you cuz it sounds like an awesome concept.

Blue Lock website