Lockitron

While unlocking your front door with your phone isn't a new idea, the Lockitron has made installing the wireless door lock much simpler.  You no longer need to replace your entire lock system, you just slip the Lockitron over the inside of your existing deadbolt lock. 

Once installed you can check the status of the lock or lock/unlock the deadbolt from just about anywhere.  If you have a family friend watching the dog while you are out of town you can add them to the list of folks who can access the lock.  While the Lockitron has a slick app for the iPhone, you can unlock the door with just about any phone that can send a text message.

If someone knocks at the door the Lockitron can send you a text message to alert you.  The coolest part, is the fact that it has Bluetooth 4 integration so it can sense your iPhone 4S or iPhone 5 and automatically unlock the door as you approach.