You can do lots of awesome things with a Raspberry Pi. Take this PebblyPi for instance. It consists of a Raspberry Pi and a Pebble Watch. You will also need a resistor, Pushover (to handle notifications), a button to act as a doorbell, and PC speakers. Knowing a bit of Python wouldn’t hurt your cause. When someone rings your door, you will get a notification on your watch.
PebblyPi is a pretty clever project, but it’s even more exciting to think about what else is possible. Thankfully, there are so many great DIY projects like this available online.
[get more information on PebblyPi]