some times ago I wrote a how to on Makezine.com
The tutorial explain how to use an Arduino and an optional IP camera to build a doorbell that sends you a Push notification on your phone and an email with a picture of the person at the door.
It's pretty simple because the "hard" part is managed by a dedicated cloud...
Here is the link to the howto:
makezine.com/projects/notifying-doorbel ... ushingbox/
and a (old) demo video:
Feel free to ask me any question
