Today, while looking through my RSS feed, I found this app called Tether for iPhone. This app cought my attention because I've been looking for something like it before. Anyways, Tether is a app that locks your Mac computer when you are far away from it and then unlocks it when you are close enough to it. It achieves this by using a low-power Bluetooth connection to your supported iOS device. I used Knock before to unlock my computer but that requires me to "knock" on my phone like I would a door, which is still really cool if you ask me. What I like about Tether is that it's free as of right now.
Tether will lock your Mac when you're not there and spring it back to life whenever you return. It's that simple!