Do you want to know who ring your doorbell when you are away from your home? If your answer is yes then this video is for you. You will attach a camera to RaspberryPi and whenever a person presses the doorbell, RaspberryPi takes a photo and put it into a folder that is in sync with Google Drive. This way you will get the picture on your smartphone.
Check out product : SMK 8mp camera module.
Watching video.