Here's a $149 gadget that you can mount over a door's deadbolt so you can turn the knob via your iphone.
Lockitron is an attachment you can place on the back of any deadbolt lock in your house that allows you to lock and unlock it remotely via your smartphone. Better than that, if you have your iPhone 5 in your pocket when you approach a Lockitron deadbolt, you don’t have to even have to use your iPhone because it will detect you via Bluetooth 4.0 and unlock automatically.
You can share access to your lock with friends and family so that if you’re not at your house and want to let them in you don’t have to worry about getting them an extra key. The sharing access feature makes it perfect for Airbnb customers.