The KitKat Clock app has a subtle but impressive feature

Dismiss an alarm before it goes off, right from the notification bar

If you're running a device with Android 4.4 KitKat (Nexus 5 or a custom ROM at this point) and set an alarm in the stock Clock app, you'll be in for a subtle little treat. Google's latest Clock app, which has received yet another facelift with a little more eye candy, now notifies you two hours ahead of when your alarm is set to go off, letting you dismiss it before you're startled by that alarm tone. The notification is silent and subtle, with the option to swipe it away, tap "dismiss now," or tap to enter the Clock app.
It's not something that everyone will use — hopefully we're all sleeping swiftly through the night — nor is it something that we haven't seen from third-party apps before, but it's features like this that remind us Google is working on even the smallest details.